M38A1 wiring harness alternatives

1952 - 1968, M38A1, M170, questions, discussions, regarding anything related to the M38a1 series.
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mcj115
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M38A1 wiring harness alternatives

Post by mcj115 » Mon Jun 20, 2022 7:50 pm

I am considering replacing the wiring harness on a recently acquired 1952 (early) M38A1. While the one in there functions it has been modified and is ~70 years old. new repro M38A1 harnesses are not cheap to say the least. This is a driver jeep and not intended to be a judged restoration vehicle; however I would like to keep it close to stock as possible.

I see there are folks recommending M35 harnesses. Other than TM references are there any good guides?
I also see there are some reasonable M170 harnesses. Is the M170 harness a good alternative? I am looking for cheap, fast and good fit (I know chose any two)! It sounds like the regulator is in a different spot but that seems like that can overcome. It would obviously be ~20 inches longer.

In others experience what quicker and better fit between the M170 and M35 harness? Am I missing any good other alternatives?


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Re: M38A1 wiring harness alternatives

Post by W. Winget » Tue Jun 21, 2022 8:52 pm

M37 would have had similar features and configuration to the jeep.
Might get one with Douglas metal connectors out there as well. Warly M35 Gasser would maybe have the steel Douglas connectors as well.
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Re: M38A1 wiring harness alternatives

Post by dpcd67 » Fri Jun 24, 2022 8:11 am

I use M35 harnesses; there are no NOS M37 harnesses on the market as far I find. There are some M151 harness out there and I have used those. Packard connectors.
Remember that all M series wiring is the same; a #18 wire goes to the left headlight whether on a tank, jeep, or submarine. Of course they have added a few hundred wires since 1950. But they are all numbered.
Of course, you have to be able to cut them and have a 4 toothed crimper and the terminal ends. But that part is easy. Easier than $800. for a new made harness.
Cheap, fast, good fit as is? Conflicting goals.
If you can find an M170; just use that and tuck the extra wire in a loop under the body with a zip tie. Or wire clip.
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Re: M38A1 wiring harness alternatives

Post by egalecov2 » Sun Jun 26, 2022 2:39 pm

The M170 harness will work - the Army Tank Guy sells a NOS M170 harness with Douglas connectors. Most of the M170s I have met have the newer Packard connectors so the M170 with Douglas connectors is an odd duck. The. M170 is longer than your M38A1 so the wires to rear will be longer. The M170 has the voltage regulator mounted to the firewall on the driver's side not mounted to a frame bracket on the on the passenger side. This will not affect using the M170 replacement harness but something to be aware of. There will be a few extra wires with the M170 harness you can ignore - if you get this far and have questions I can give you the wire numbers. Be aware that the Tank Guy's M170 harnesses have some age so I would assemble the Douglas metal shells with some silicon grease or similar lubricant.

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Re: M38A1 wiring harness alternatives

Post by Bill H. » Sun Jun 26, 2022 6:57 pm

egalecov2 wrote:
Sun Jun 26, 2022 2:39 pm
The M170 harness will work - the Army Tank Guy sells a NOS M170 harness with Douglas connectors. Most of the M170s I have met have the newer Packard connectors so the M170 with Douglas connectors is an odd duck. The. M170 is longer than your M38A1 so the wires to rear will be longer. The M170 has the voltage regulator mounted to the firewall on the driver's side not mounted to a frame bracket on the on the passenger side. This will not affect using the M170 replacement harness but something to be aware of. There will be a few extra wires with the M170 harness you can ignore - if you get this far and have questions I can give you the wire numbers. Be aware that the Tank Guy's M170 harnesses have some age so I would assemble the Douglas metal shells with some silicon grease or similar lubricant.
Who is the Army Tank Guy? Contact information? TIA
Bill H.

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1962 AMC M422A1
1965 Stevens M416B1

2 Timothy 3:1-5

Ron D
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Re: M38A1 wiring harness alternatives

Post by Ron D » Sun Jun 26, 2022 7:19 pm

Hi Bill,
"Army Tank Guy" is the fleabay handle for Brent Mullins at Brent Mullins Jeep Parts (BMJP) of College Station, Texas.
Great guy and one of the venerable military parts vendors we have supporting this hobby.

Along with MWM, AJP, QTM, RFJP (of course!) and a few others.

If it helps, see here:
https://www.ebay.com/str/mullinsjeepparts
https://www.mullinsjeepparts.com/
Ron D
1952 M38
1951 M100

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Bill H.
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Re: M38A1 wiring harness alternatives

Post by Bill H. » Sun Jun 26, 2022 7:25 pm

Ron D wrote:
Sun Jun 26, 2022 7:19 pm
Hi Bill,
"Army Tank Guy" is the fleabay handle for Brent Mullins at Brent Mullins Jeep Parts (BMJP) of College Station, Texas.
Great guy and one of the venerable military parts vendors we have supporting this hobby.

Along with MWM, AJP, QTM, RFJP (of course!) and a few others.

If it helps, see here:
https://www.ebay.com/str/mullinsjeepparts
https://www.mullinsjeepparts.com/
Thank you!!!
Bill H.

"Each shall seek his own kind, in other words, a bird may love a fish but where would they build a home together?" Tevya, Fiddler on the Roof

1962 AMC M422A1
1965 Stevens M416B1

2 Timothy 3:1-5

Ron D
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Re: M38A1 wiring harness alternatives

Post by Ron D » Sun Jun 26, 2022 7:32 pm

You're welcome!

By the way....what does "TIA" mean for us internet acronym challenged people?
Ron D
1952 M38
1951 M100


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