Identifying Differential

Hey all,

I have a leaky axle seal at the passenger side rear axle flange so I want to replace it, but I want to make sure I get the right ones. I looked online and autorestomod made a video on identifying 9inch and 8inch diffs 

but mine doesn't fit the description or the example they have on the channel.
Figured y'all would probably be able to help me. Also how bad does that weep look? Havent noticed any fluid on the ground from it yet, will get the diff fluid swapped out and new gaskets for it after I find out what diff it is. If this helps my vehicles original axle code is a 6 (3.00:1 ratio), but the original engine was a code H 351 2V, but there's a 429 in it now and the original tranny was a code X FMX Automatic but theres a C6 in it now. 

Here are pics I took this morning of the rear.





Also heres some pictures with the axle out. There was sludge just on the inside of the axle flange as demonstrated in one picture with my finger. Is that a side effect of fluid being exposed to water and stuff? Should I be more concerned about it? Was going to replace the seals and bearings and get the fluid/gaskets replaced.

I'm not sure I can be of any help, no idea what that is, but first, what year is it and what model?

If it's an H code, it ought to be a 9 inch from what little I know, but it looks nothing like the 9" I have in my 71 M code. Perhaps it a switch out too? Perhaps a truck rear axle or from another car.

Can't find my pictures right now, will post if I find them.

Geoff.

Hope this helps. this is a stock Ford 9" out of my car.

Definitely need more information about your car, year, engine, model, etc.

To me it looks like an early 8", but hard to tell from the pictures. Need to see what it looks like from the front. Does it have a small metal tag under one of the bolts?

This article might help:

http://kevinstang.com/Ninecase.htm

The 9" has a bump out to clear the ring gear on the back of the housing. That does not look like a 9" to me. Also the fill plug is in the center section on the front left side. Looks like someone just put something in. First year for 9" was 1957.

Thanks for the links guys. Yeah this thing doesn't match the descriptions of the standard ford 8 and 9 inch rear axles, so unless its some special production run, idk what the previous owner put in. I'll try an see if there's a tag or something on it. I wonder if perhaps its from the same vehicle that the motor and transmission came from. What all ran the 429/460 motor and a C6 transmission? Might be able to narrow it down, though I am aware that both had a long and numerous production run.

I was helping a friend the other day with his 64 1/2 mustang vert as we were locating drip sources from the drive train while up on a lift. Car had 260 with C4.

The rear end unit in your pic appears identical to his (especially the filler plug in the pumpkin). Could be one of the previous owner's sold the original 9" from your car and installed an early 8" unit.

Looks like an early 8” to me.

Thanks for the links guys. Yeah this thing doesn't match the descriptions of the standard ford 8 and 9 inch rear axles, so unless its some special production run, idk what the previous owner put in. I'll try an see if there's a tag or something on it. I wonder if perhaps its from the same vehicle that the motor and transmission came from. What all ran the 429/460 motor and a C6 transmission? Might be able to narrow it down, though I am aware that both had a long and numerous production run.

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Anything with a 429/460 would have had a 9" or larger rear. Your axle appears to be a 65-66 Mustang 8" housing. Large flat on bottom of center section, two dimples with fill plug and tapered tube ends. No strength difference between it or any other 8".

I thought it looked like the 9” from a 63 Galaxy, like the one shown in the link? They show a 9” with a drain plug and two dimples on either side. Maybe I was looking at the wrong picture? Anyway hopefully you can figure it out. Good luck.

8" and 9" rear ends prior to 1968 had the filler in the rear of the housing. 8" were more of an oval shape, these two factors are why we're all saying it looks like an early 8".

I thought it looked like the 9” from a 63 Galaxy, like the one shown in the link? They show a 9” with a drain plug and two dimples on either side. Maybe I was looking at the wrong picture? Anyway hopefully you can figure it out. Good luck.

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+1 if you also look at the poster’s pic his axels appear to taper at the ends indicating an early 9”.

Don't ya just love it when someone decides to put whatever they can find in a classic car? 

I would have thought that IF the PO decided to transplant a 429/460 with (presumably) it's matching C6 trans, he would also have installed the rear axle out of the same vehicle, unless it was from a truck. The car was an H code, so it would have had the 9" I think. That would have been better to leave in if it was not broken.

The original poster needs to offer more info. Does the car still have the original door data sticker? What axle does it list? He still did not say what car he has unless I missed it without rereading.

Geoff.

If the OP can put a deepwell socket on the bottom two nuts for the center section, it's an 8". If not, it's a 9".

Thanks for more info.

For those asking its a 1971 Mach 1, didn't really think it would matter what the car was since I gave the original Engine, Transmission and Differential codes from the factory listed next to the VIN that I looked up with this handy link https://www.7173mustangs.com/misc.php?page=1971

Having looked at the 63 Ford Galaxy differential I am starting to think that might be the diff that was installed on my 71. I have no idea why they would choose that, but I guess it was what was available at the time. Its not like I bought this thing fully restored. It was running and in decent condition internally and externally.

I will continue to research the Galaxy line of ford diffs to see if I can track it down. Hopefully I will have time to see if there is a stamp present that will identify it.

While you're under there looking for a tag, look at the bottom front at the locations Hemikiller pointed out, that's a sure indication of if it's a 9" or not.

A '63 Galaxie would be a strong possibility, as it has the same width axle as '71 to '73 Mustangs.

The axle code just indicates the ratio and whether it's a traction axle, not what type or size, for many years and models of Ford cars.

One more question, do you yet know what the ratio is? Also, is it a tration-lok type or open?

I know, more questions!

Geoff.

He said earlier that it came with a code 6 axle, 3.00:1 open.

Came with a code 6, but who knows whats in it. Fingers crossed that the stamp is still with it somewhere. Um, when I had it on stands the other day if I moved one wheel the other would turn too, but then it stopped after a little while and just the 1 wheel would turn.