Feedback on Boss i'm interested in

[secluff]

Hello Geoff,
The '65-72 Master Parts Catalog (MPC) can sometimes be more than a little confusing. Much of it is from not removing any references to the stillborn '71 Boss 302, referred to as a 302 Special in the '71 Mustang applications. The transmission for the '71 Boss 351 is RUG-AV1, which is a 2.78 wide-ratio transmission. This transmission is Ford part # D0ZZ-7003-D, which was replaced with a D2ZZ-7003-D (RUG-BJ). The D2ZZ-D (RUG-BJ) was cataloged for the '72 R and Q and was utilized as the replacement for the RUG-AV1 used for the '71 Boss and limited availability Q 351.
When looking at the '71 transmission application RUG-AV1, mentally remove the '302 Special" reference, and you will see the two vehicles 351 4B (M) and 351 Spl (R) that used this transmission. For the RUG-AW1 application, remove the 302 Special references, and it leaves the second transmission choice for the 351 4BL (M). The '71 M 4sp I drove had the RUG-AV1 trans with a 3.50 gear, so the differential gear probably was the deciding factor on what transmission the M code left the factory with.
The two transmissions listed in the '72 R & Q applications, before and after 12/1/71, result from more government "Watch Dogging" over us. 12/1/71 is the date Ford started installing the Federally mandated 1972 seat belt warning light/buzzer system. '72 vehicles built before 12/1/71 received the D2ZZ-7003-D (RUG-BJ). '72s (built after 12/1/71) and '73 Mustangs received the D2ZZ-7003-H (RUG-BJ1). This transmission had a seat belt warning sensor switch in the left front of the transmission case. This switch was also used on three and 4sp Torino, Mustang, Maverick, and '73-75 Broncos. The switch functioned the same as the automatic cars when you placed the vehicle in gear without fastening the seat belts. This is the only difference between the two transmissions. There was a plug Ford released for the transmission case when it was used to service a car built before 12/1/71 that did not use the switch.
OK, that is enough number and letter salad for transmissions today!

@pavestone2460,
The seller is not giving this car away; this is your hard-earned money, whether Australian or U.S. dollars! I would definitely perform a thorough hands-on inspection, starting with the VIN discrepancy. The info you have received so far is excellent. To check the numbers matching claim, you can check for a partial VIN on the left rear of the block right below where the head mounts to the block. The front upper flange, where the transmission mounts to the bell housing, is another area to check for a partial VIN. The partial VIN will have 1(1971) and F for the assembly plant (Dearborn) and the six numbers of the consecutive serial number. So if the Vin on the title and Ford invoice shown are correct for this vehicle, the partial VIN would read "1F 180926".
Some members here have been burnt on fake Boss parts, such as carburetors, distributors, Rev limiters, and dipsticks. When a genuine Boss 351 dipstick that retailed for under $5.00 when discontinued can bring $500.00 to $600.00 and above on eBay, the temptation is great for these * %♣&♫¢ "THIEVES" to manufacture/clone said fake parts!! The rev limiter on the right front shock tower should have an ink stamp DOZF-12450-B, 6150 RPM if O.E. The carburetor on the Motor Trend link has an incorrect tag. The D1ZF-ADA is for a 302 2BL carb. D1ZF-ZA is the correct O.E. carb. I'm surprised the experts at Motor Trend missed that. The O.E. distributor is D1ZF-12127-DA.
Besides myself, many forum members here have a good handle on these numbers, including several Boss owners. Regardless of U.S. or Australian dollars, that is a costly vehicle. During your inspection, if you feel you need more information or clarification on something they may not know, you know what group to contact!
Please keep us in the loop on how things go. We would really like to add another Boss owner to our ranks!

 

[Stevieray]

Looking over the pics and documentation, the Boss appears to be legit. In saying that…..I‘m a bit concerned over the quality of restoration. The steering column finish condition is mentioned by another member. I have some concern over the engine compartment pictures. I pulled my drivetrain out several years ago for the first time for overhaul. Pictures are posted on this site. I ended up replacing the two front fender aprons due to rust. Not expected but found during the process. $120k is a lot of money. I would either inspect the car myself or hire a Mustang expert.

 

[Hemikiller]

While the close ratio RUG-AWx tranmissions were listed in the MPC, Marti's book shows only the Code 5 wide ratio being used behind the 351 in the 71-73s. Code 6 close ratio were limited to the 71 429 cars.

The -Ax to -Bx toploader update included a change in the main case casting from C8AR to D2AR. The D2 casting implemented the boss for the switch in between the 3-4 and Reverse shift levers.

C8AR case



D2AR case

 

[Stanglover]

Hello Geoff,
The '65-72 Master Parts Catalog (MPC) can sometimes be more than a little confusing. Much of it is from not removing any references to the stillborn '71 Boss 302, referred to as a 302 Special in the '71 Mustang applications. The transmission for the '71 Boss 351 is RUG-AV1, which is a 2.78 wide-ratio transmission. This transmission is Ford part # D0ZZ-7003-D, which was replaced with a D2ZZ-7003-D (RUG-BJ). The D2ZZ-D (RUG-BJ) was cataloged for the '72 R and Q and was utilized as the replacement for the RUG-AV1 used for the '71 Boss and limited availability Q 351.
When looking at the '71 transmission application RUG-AV1, mentally remove the '302 Special" reference, and you will see the two vehicles 351 4B (M) and 351 Spl (R) that used this transmission. For the RUG-AW1 application, remove the 302 Special references, and it leaves the second transmission choice for the 351 4BL (M). The '71 M 4sp I drove had the RUG-AV1 trans with a 3.50 gear, so the differential gear probably was the deciding factor on what transmission the M code left the factory with.
The two transmissions listed in the '72 R & Q applications, before and after 12/1/71, result from more government "Watch Dogging" over us. 12/1/71 is the date Ford started installing the Federally mandated 1972 seat belt warning light/buzzer system. '72 vehicles built before 12/1/71 received the D2ZZ-7003-D (RUG-BJ). '72s (built after 12/1/71) and '73 Mustangs received the D2ZZ-7003-H (RUG-BJ1). This transmission had a seat belt warning sensor switch in the left front of the transmission case. This switch was also used on three and 4sp Torino, Mustang, Maverick, and '73-75 Broncos. The switch functioned the same as the automatic cars when you placed the vehicle in gear without fastening the seat belts. This is the only difference between the two transmissions. There was a plug Ford released for the transmission case when it was used to service a car built before 12/1/71 that did not use the switch.
OK, that is enough number and letter salad for transmissions today!

@pavestone2460,
The seller is not giving this car away; this is your hard-earned money, whether Australian or U.S. dollars! I would definitely perform a thorough hands-on inspection, starting with the VIN discrepancy. The info you have received so far is excellent. To check the numbers matching claim, you can check for a partial VIN on the left rear of the block right below where the head mounts to the block. The front upper flange, where the transmission mounts to the bell housing, is another area to check for a partial VIN. The partial VIN will have 1(1971) and F for the assembly plant (Dearborn) and the six numbers of the consecutive serial number. So if the Vin on the title and Ford invoice shown are correct for this vehicle, the partial VIN would read "1F 180926".
Some members here have been burnt on fake Boss parts, such as carburetors, distributors, Rev limiters, and dipsticks. When a genuine Boss 351 dipstick that retailed for under $5.00 when discontinued can bring $500.00 to $600.00 and above on eBay, the temptation is great for these * %♣&♫¢ "THIEVES" to manufacture/clone said fake parts!! The rev limiter on the right front shock tower should have an ink stamp DOZF-12450-B, 6150 RPM if O.E. The carburetor on the Motor Trend link has an incorrect tag. The D1ZF-ADA is for a 302 2BL carb. D1ZF-ZA is the correct O.E. carb. I'm surprised the experts at Motor Trend missed that. The O.E. distributor is D1ZF-12127-DA.
Besides myself, many forum members here have a good handle on these numbers, including several Boss owners. Regardless of U.S. or Australian dollars, that is a costly vehicle. During your inspection, if you feel you need more information or clarification on something they may not know, you know what group to contact!
Please keep us in the loop on how things go. We would really like to add another Boss owner to our ranks!
View attachment 79209
View attachment 79210

Steve, thank you for clarifying the gearbox number confusion. I learn something new every day. I still wonder why Ford did not put a close ratio box in the Boss. But was it an option that could be ordered in a Boss or Mach 1?
I know I wish my Mach had a close ratio box, but alas it doesn't.
This thread got off track by a mile, but all great info for us and our new Aussy friend.

 

[Stanglover]

While the close ratio RUG-AWx tranmissions were listed in the MPC, Marti's book shows only the Code 5 wide ratio being used behind the 351 in the 71-73s. Code 6 close ratio were limited to the 71 429 cars.

The -Ax to -Bx toploader update included a change in the main case casting from C8AR to D2AR. The D2 casting implemented the boss for the switch in between the 3-4 and Reverse shift levers.

C8AR case

View attachment 79219

D2AR case

View attachment 79218

Hemikiller, The CR box behind a 429 makes sense, but from the Marti Tagbook I have, he only list in 71, 5 as wide ratio, 6 as close ratio. No engine reference that I see unless I missed it which is quite possible. He also list RUG-AZ1 close ratio for the 71 429.
Regardless, I continue to learn from the best, Thanks.

 

[Sheriff41]

Looking over the pics and documentation, the Boss appears to be legit. In saying that…..I‘m a bit concerned over the quality of restoration. The steering column finish condition is mentioned by another member. I have some concern over the engine compartment pictures. I pulled my drivetrain out several years ago for the first time for overhaul. Pictures are posted on this site. I ended up replacing the two front fender aprons due to rust. Not expected but found during the process. $120k is a lot of money. I would either inspect the car myself or hire a Mustang expert.

Definitely a significant amount of cash, but $120K AUS is about $80K US. That seems to be toward the lower end of B1's for sale in the US.

 

[Hemikiller]

Hemikiller, The CR box behind a 429 makes sense, but from the Marti Tagbook I have, he only list in 71, 5 as wide ratio, 6 as close ratio. No engine reference that I see unless I missed it which is quite possible. He also list RUG-AZ1 close ratio for the 71 429.
Regardless, I continue to learn from the best, Thanks.

I'm going off the production numbers in his Mustang by the Numbers book.

 

[william binegar]

The correct tranny for a Boss 351 is the RUG AV1. The other trannys were either produced before Boss 351 production (RUG AV which was used in 1970 only) or after production (RUG BJ, they weren't used till 12/1/1971) way after 1971 mustang production had ended. A RUG BJ would be correct for a 1972 351 HO Mustang ( 1972 Special which what the ford parts book used for terns for boss engines, like the Boss 302 , Boss 429 and the Boss 351, and the 1972 351 HO. I looked at the pictures of this car, and although there could be other things not correct. the only thing i noticed was the distributor has the wrong vacuum advance, ( has a 1970 advance) which could mean it also has the wrong distributor. Plus I can't see the dot after the 4 in the corner of the heads, it could be there, I just don't see it. The serial number shown is a known Boss 351

 

[giantpune]

Is it just me, or does the trunk weather strip appear to be installed incorrectly. Ford assembly manual says the joint should be at the center of the bottom, just over the fuel filler. In this red car, the joint is centered at the top. I would assume the split being at the top would allow water into the trunk.

 

[Stanglover]

I'm going off the production numbers in his Mustang by the Numbers book.

Ah, I don't have that book. Seems like there might be a bit of difference between his books.

 

[Stanglover]

The correct tranny for a Boss 351 is the RUG AV1. The other trannys were either produced before Boss 351 production (RUG AV which was used in 1970 only) or after production (RUG BJ, they weren't used till 12/1/1971) way after 1971 mustang production had ended. A RUG BJ would be correct for a 1972 351 HO Mustang ( 1972 Special which what the ford parts book used for terns for boss engines, like the Boss 302 , Boss 429 and the Boss 351, and the 1972 351 HO. I looked at the pictures of this car, and although there could be other things not correct. the only thing i noticed was the distributor has the wrong vacuum advance, ( has a 1970 advance) which could mean it also has the wrong distributor. Plus I can't see the dot after the 4 in the corner of the heads, it could be there, I just don't see it. The serial number shown is a known Boss 351

Good info, thanks for your knowledge and my education.

 

[pavestone2460]

just want to provide an update after inspecting it. exterior condition is good - no scratches, dents, dings and paint looks good as does the wheels. checked the wheel arches and along the bottom and i couldn't see any rust, i also looked in the trunk.

interior appears to be original. seats are in good condition but the rest i'd describe as showing it's age, but nothing of significant concern. the carpet could probably do with replacing.

under the hood i verified as much as i could - carb looks to be genuine although it wasn't until i had the air cleaner back on i realised i didn't check for a tag. manifold is genuine. couldn't find a part number on the dizzy. i wasn't able to check head or block numbers due to how tight it was in there, nor could i attempt to locate the vin on the back of the engine. i noticed fuel on the manifold while i was checkig the carb, so it's obviousky leaking. looks like the ps pump has a leak too, although they say they replaced the hoses. the oil filter was an autolite and had blue overspray on it.

they say they don't have a hoist so i wasn't able to look underneath it. i also wasn't able to drive it because they're saying there's an issue with the lock in the drivers door needing to be replaced so it can't be opened at this time.

they knew very little about it, and admited that they dont normally deal with muscle cars or older cars. i've asked if they can get details from the owner about what they've done with it since it's been in australia (which i verified from paperwork is 2014) and what was done as part of the restoration. to my amatuer eyes it mostly looks original. i've also asked if the owner has any pics of the engine/trans with the vin on it.

not sure how i feel. mostly overwhelmed and in over my head, i think. maybe my expectations are too high for a 50+ yr old car.

 

[Electric Wizard]

It sounds like you're underwhelmed right now from what you saw. I would too if I couldn't drive it because the door wouldn't unlock? Were you looking for a Boss or you stumbled across it and now you are trying to figure out if you should pay up just because it is a Boss? You might do better cost wise with a Mach 1 (non Boss).

 

[tpj71mach]

It seems a bit convenient that they do no have a hoist and you can't drive it because the drivers door wont open. I would tell them I'm willing to climb over the console to drive to a hoist so I can see the bottom and verify engine and trans numbers before I spend that kind of money. That's just what over 40 years in the car business has done to me, sadly I trust no one, I have heard too may lies over the years. Although, my perspective is from the opposite direction, customers lying to the dealer. Customer's would tell me that they have owned a car since new and the car was never in an accident when I can see from 40 feet away the front end is a different color and doesn't line up with the body at all and the Carfax shows a major accident a year earlier. Anyway, if they are reputable they will understand your need to verify the condition and authenticity before you buy.

 

[giantpune]

For what they're asking for it, they sure dont sound too interested in actually selling it. There may be more things wrong with the car they just didn't want you to discover it you'd started driving it. For the kind of money they're asking for this car, they should be expecting the buyer is gonna want to go over it with a fine toothed comb, inside and out, over and under.

Either way, its never a bad idea to get a 3rd party pre-purchase inspection unless you yourself are an expert.

As far as you being underwhelmed, I think that could be a combination of things. First, the can does sound like it needs a bit of love. Leaking fuel, door lock not working, and not being able to drive it. You only get one chance to make a first impression, and that car left a negative one. But also, you'll have to go into it with realistic expectations. Its a 52yr old car. Even if it was a perfect example of a 1973 mustang, it will still be loud, squeeky, rattly, and smelly. It won't seal up perfectly from the outside air. Everything in it is mechanical and analog. By today's standards, it really isn't even all that fast.

 

[Sheriff41]

@pavestone2460 do you have access to the Mustang community in your area? If you haven't reached out to them yet, The Mustang Owner's Club of Australia may have some member's in your area that could inspect the car with you. They may even be familiar with the car if the owner was a member.

While any 50+ year old car will have issues, if they are minor, you may want to consider if they are really showstoppers for you. If you can address them yourself, you may be able to increase the value of the car while you enjoy it. Finding Boss Mustangs in the US is challenging enough, I imagine they are few and far between in your country!

 

[ib4stangs]

So... I googled the serial numbers in the sellers ad, and these 2 links popped up!

https://www.mecum.com/lots/169695/1971-ford-mustang-boss-351-fastback/
https://car-from-uk.com/sale.php?id=109832&country=us

 

[giantpune]

https://car-from-uk.com/sale.php?id=109832&country=us

Sale price: $64,900.00
That's not a bad turnaround for somebody.

 

[Stanglover]

A side story for all you Boss 351 lovers that might make you weep.
Yesterday, I was at a car show with the only 71-73 there let alone a Mach 1, when I guy came up to me and started off as many do. "I had one of these back in 1971 when I lived in Nova Scotia" I think that's where he said, I wasn't really paying attention. Then he said, "well , it wasn't a Mach 1 but a Boss 351. By 1974 it had rusted to bits in the salt air out there and I scrapped it". Well I guess we know at least one didn't make it.

 

[ib4stangs]

That's when I would have asked, "Have anything left from it?"