73 alternator wiring Harness

Question: I have a 73 Mustang Convertible W/O gauges but I have factory air. Which harness should I purchase I am a little confused picking between the 42-61 amp harness vs the 70 amp harness. How do I tell which one I have. The car is in the shop right now and I wanted to order it online. Thanks for your help

Question: I have a 73 Mustang Convertible W/O gauges but I have factory air. Which harness should I purchase I am a little confused picking between the 42-61 amp harness vs the 70 amp harness. How do I tell which one I have. The car is in the shop right now and I wanted to order it online. Thanks for your help

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Pretty sure this is the one you want...

http://www.virginiaclassicmustang.com/73-WITHOUT-GAUGES-V86-CYLINDER-WITH-AIR-CONDITIONING-425561-AMP-ALTERNATOR-ALTERNATOR-HARNESS-P5385.aspx

Question: I have a 73 Mustang Convertible W/O gauges but I have factory air. Which harness should I purchase I am a little confused picking between the 42-61 amp harness vs the 70 amp harness. How do I tell which one I have. The car is in the shop right now and I wanted to order it online. Thanks for your help

Click to expand...

Pretty sure this is the one you want...

http://www.virginiaclassicmustang.com/73-WITHOUT-GAUGES-V86-CYLINDER-WITH-AIR-CONDITIONING-425561-AMP-ALTERNATOR-ALTERNATOR-HARNESS-P5385.aspx

Click to expand...

Thanks!!

Pardon me for re-using this thread

How can I tell howmany amps my alternator has?

And my car has no gauges but used to have airco. Some day I'd like the airco back in but right now it's not. Can I still use a harness for a car with airco?

Thanks!

It's stamped on the side of the alternator near the main mount. It'll show the voltage and amperage, and be something like 12V 40A.

I guess it's like that with yours but I couldn't see anything like that stamped on the side of mine :-/

Probably a rebuilt, they often remove the markings, the cases are all the same size. The only way you'll be able to get an approximation is to leave your headlights on for 30 minutes, connect a ammeter between the alternator and the battery and see what it is putting out.

OK, so I have a 351C, 8 cyl. When browsing CJP I found this:

- http://www.cjponyparts.com/alternator-wiring-harness-6-cyl-w-o-gauge-and-ac-exc-70-amp-1973/p/WALT9C/

70Amp which is def. enough but that says 6 cyl even though it looks exactly like what I have.

So I continued my search and found this one which looks the same but says 8 cyl. 42-61 Amps:

- https://www.npdlink.com/store/products/wire_loom_alternator_to_voltage_regulator-175763-1.html

Both harnesses match the colour coding from the wiring diagrams and the connectors seem to match. Then I read the reviews under the CJP harness and guess what? Some dude has the same harness as I do and ran in to the same issue!

So... Is there really a difference between the 2 harnesses? What makes the 6 cyl different from the 8 cyl? I think it's nonsense...

The lengths of the wires are likely different.

OK, so I have a 351C, 8 cyl. When browsing CJP I found this:

- http://www.cjponyparts.com/alternator-wiring-harness-6-cyl-w-o-gauge-and-ac-exc-70-amp-1973/p/WALT9C/

70Amp which is def. enough but that says 6 cyl even though it looks exactly like what I have.

So I continued my search and found this one which looks the same but says 8 cyl. 42-61 Amps:

- https://www.npdlink.com/store/products/wire_loom_alternator_to_voltage_regulator-175763-1.html

Both harnesses match the colour coding from the wiring diagrams and the connectors seem to match. Then I read the reviews under the CJP harness and guess what? Some dude has the same harness as I do and ran in to the same issue!

So... Is there really a difference between the 2 harnesses? What makes the 6 cyl different from the 8 cyl? I think it's nonsense...

Click to expand...

This information from 72 wiring diagram in data section.  I think the harness is the same except for wire size.

OK, so I have a 351C, 8 cyl. When browsing CJP I found this:

- http://www.cjponyparts.com/alternator-wiring-harness-6-cyl-w-o-gauge-and-ac-exc-70-amp-1973/p/WALT9C/

70Amp which is def. enough but that says 6 cyl even though it looks exactly like what I have.

So I continued my search and found this one which looks the same but says 8 cyl. 42-61 Amps:

- https://www.npdlink.com/store/products/wire_loom_alternator_to_voltage_regulator-175763-1.html

Both harnesses match the colour coding from the wiring diagrams and the connectors seem to match. Then I read the reviews under the CJP harness and guess what? Some dude has the same harness as I do and ran in to the same issue!

So... Is there really a difference between the 2 harnesses? What makes the 6 cyl different from the 8 cyl? I think it's nonsense...

Click to expand...

Vinnie,

Here is a previous link on alternator info that you may find useful: https://www.7173mustangs.com/thread-1973-mustang-alternator-applications

Vinnie, another one of those subjects where you can get lost in the numbers. The majority of 71-73 Mustangs had what was referred to as the small case alternator (38, 42, 55, 61 amp) and had the electrical connections at the rear of the case. The large case (70, 90, 100 amp) had the connections at the top of the housing and was twice the size of the standard alternator. Most of the ordering info on these cars show 55 and 61 amp alternators with AC and rear window defroster. There are part listings for 70 amp wire harness and alternators for these cars. So whatever it took to qualify the vehicle to receive one, they were production installed at some point. You would think heavy load electrical needs would get the larger alternator. I had three different Gran Torino Sports. Two were Q code identically equipped cars, but one had a 55amp alternator and the other had a 70amp. The third was a 429 car with AC, but no power seats, windows, or rear defrost, but still had the large case 70amp alternator. Other than on Police cars I don't really know how the engineers came up with what qualifiers were used for alternator selection. I had a lot of trouble with the brush connection on the wire harness of the 70amp alternator so when I replaced the 429 with a CJ engine I changed the brackets, wire harness and installed a 55amp alternator.

With the newest of our cars now 44 years old, there are probably not a lot left with the original alternator. Most were replaced with generic one size fits all units. It was that way even with the Ford re-man units. So the chance of having one that has legible original markings are slim. Most received the same rectifier plates, armatures and stators regardless of what the original ratings were. I have some illustrations that show the larger size of the "Big" alternator and the top connections and the small case where the Id numbers typically were and the "Rear" connections. First two are the small case and third is the 70amp "Big" case.

Clear as crystal now. Thanks for all the responses!

Steve: Those photos make everything very clear, thanks a bundle! I have a smaller alternator so less than 70 amps which means the NPD harness will work for me.

Don: After seeing Steve's first photo I know where to look for the description. There seems to be only a fraction of the text left on mine, unless I can find a way to make it all visible or maybe they just didn't stamp hard enough. I'll have another look.

Anyway, Since the NPD harness is for 42-61 I'm quite positive that one will work for me.

Thanks guys

Went to have a closer look at the alternator today. I think the guy stamping the letters was having a bad day...

That's typical of a rebuilt alternator. They grind or sand blast the original information and stamp in their own.