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I'm looking into building my own harness and was planning on disassembling a harness from a 5 ton truck and using its components for the m37. I know the connectors are different types, i.e. metal versus rubber, but that shouldn't matter. I can get the 5 ton harness for 40 bucks. Any thoughts from the group?

I guess that will work but I am not an expert.

You should be using the metal Douglas connectors if you want to be period correct. If not, the rubber packard ones will be ok.

refit1701,

I planned on using the metal connectors. I'm also going to build a harness for my m151-A1. I had a guy offer me a NOS 3 lever switch cannon plug for 40 bucks. I was going to buy them until I found these harnesses cheaper. My plan is simple, I'll cut the black wrap off the wire bundle and re-route for my application. This should give me an up to date harness for the m37 and allow me to add turn signals. The only problem I see is the spider harness on the m37. I think I can eliminate the spider harness and use the gauge wires from the 5 ton harness to connect directly to the m37 gauges. This should eliminate the need for the spider harness. Just a thought for now.

The spider harness is for the power to the gauges.

Does the 5 ton trucks use a spider harness or is the gauge wiring part of the harness?

I'm sure someone on here knows about the 5 tons, but I don't know myself if they use a spider harness. Except for the volt meter, the gauges have 2 wires, one from the harness for each function and one from the spider harness for power. A spider harness would be fairly simple to make with the right connector with multiple terminals.

If I recall correctly all the removable instrument cluster setups used the spider for power in to the gages from the main switch on wire # 27. The differences in spiders being the total terminal count. IE 4 leads vs 5.

If you have the time and enjoy building a harness your plan will work just fine.

I invested in a Vintage Wirng of Maine harness for my AF truck. I will likely either build one or modifiy a harness for my M151 project. So you aren't doing anything unusual, believe me.

The important issue is how old this $40 harness is?? Even though the insulation may appear fabulous, you may find it will deteriorate and start to crack very quickly. The same thing would apply to the rubber packard shells. A lot of work in transforming the harness to fit an M37 only to realize the insulation is cracking in a short while. I've seen that happen many times. The truth is this, exposed to the elements, the insulation on NEW mil spec wiring has done well if it holds up decent for 10 years. Stored mostly indoors, it does better. The thing is always this, we never know how long NOS harness has been in storage, my luck has been this with NOS harness, once it is pulled from storage, installed, and introduced to the elements, it goes down hill quickly. We custom build a lot of wiring harness for our builds, longivity will be MUCH better using new current production wire with GXL insulation, I simply would advise against using mil spec wire altogether, technology has advanced way past that stuff these days.

Does anyone have plans for making the harness.
Thanks,

http://m37.crwdesigns.com/favorite.htm

Look here. Scroll down a bit to the electrical section. There are several diagrams.

Thanks,
I am looking for the lenghts and such of each wire. Couldnt find on that site.

m-11 wrote:I'm looking into building my own harness and was planning on disassembling a harness from a 5 ton truck and using its components for the m37. I know the connectors are different types, i.e. metal versus rubber, but that shouldn't matter. I can get the 5 ton harness for 40 bucks. Any thoughts from the group?

Yes the 5 ton uses the spider harness behind the dash......................where are you getting a 5 ton harness for $40.00???? PLEASE SHARE!!!!!!! M62, M52A2 and a M54A2C owner!!!!

Gerry wrote:Thanks,
I am looking for the lenghts and such of each wire. Couldnt find on that site.

I'm not sure where to find that info. You might try to get a used harness to use as a pattern. One which won't work but will provide the lengths.

Thanks,
I was thinking that. Do you need a special crimp tool to atach the ends for douglas connectors?