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What is the difference between the 100.00 wiring harnesses and the 500.00 universal harnesses. I have to rewire my 52 1/2 ton and I am a little puzzled. And another thing, I read an article that suggested that I would need to upgrade the condenser if I went to a 12 volt system. Can anyone comment?

aphi2,

I think that there were recent discussions on both these topics in this forum.

The $100 wiring harness (perhaps from Chevy Duty) is excellent if you have a stock set-up (or just modifications for an alternator and/or turn signals).

The universal harness most likely allows for more modifications (additional electrical items) and might have additional fuses.

I did not change my condenser when I switched to 12v (never had a problem). If you are using the stock ignition set-up (with points), you will have to add a ballast resister in the lead from the ignition switch to the coil (or use a 12v coil with the resister built-in).

Good luck,

Tim

Just finished doing what you describe to a 52 1/2 ton Chevy. I ued the Chevy Duty alternator harness. But if I had to do over would have got an American Wire harness with a fuse panel. Stay away from the $450. Ron Francis or the other nite mare popular one everybody talks about. If you get the chevy Duty one save your stop and tail lite fuse block on the firewall, replace the 20 amp fuses with 10 amp. I would also suggest to add a fuse to the headlight system, heater and radio if you have one. Don't forget to change your coil to a 12 volt internal resister (NAPA)as well as the light bulbs. I changed out guages to electric Stewart Warner cluster guage and speedo. The Cluster has a voltmeter perfect for the alternator. Generators have an amp meter orig truck guage. I understand you can use the orig amp guage but need to do something to the guage wiring to use. I do not know how, and the Chevy duty instructions are awful for a beginner. Which ever wiring harness you end up with I would first have them fax you the instructions to see if it is detailed enough for you. I would also change out the gas tank sender unit to a 12 volt. Chevy Duty has those. If you use a one wire alternator and the Chevy Duty Harness tape up all the wires going to the alt except the big #10 wire. To make a one wire work follow the big #10 wire inside the cab and splice in another 10 wire run back out the wiring harness hole in the dash bring it over to the battery pole on the starter selinoid. Good luck.
t

It all depends on how much you want to pay for convenience. Tim is right, the $ 100 jobs are great if you have a stock set up. In my case, I had a few variables to deal with. My truck has a long bed so the tail light wires needed to be longer..I also have a Hydramatic Tranny which adds a neutral safety switch and a carb with an electric choke. I also wanted the directionals wired into the loom as well. I bought my harness at Ynz in California .. I talked my requirements over with them on the phone before they built it. Everything fit perfectly and I did not have to cut or modify anything. The instructions were clear and easy to follow. I paid more than a hundred bucks but as I said earlier, you pay for convenience. Check around and ask questions, you will find the one you need..