Opinions on using original wiring harness in restoration
 

I am doing a very thorough restoration on my 67 gmc. I have all the original wiring and it is all unmolested and looks like it's in decent shape. Now that being said it's 40 years old. My once is some of the new harnesses have modification for newer stuff built in like internal regulators and I want to keep my truck completely stock wiring. Am I looking for trouble reusing my stock harness. I did get new wiring for the tail lights and that intermediate harness from the firewall and some accessory stuff that are stand alones. Any opinions?

Re: Opinions on using original wiring harness in restoration
 

my original harness in my 67 was and is in great shape and i did the exact same thing with no issues, bypassed the external regulator, added HEI and H4 lighting and external fan and relays. I also lengthened the rad support harness to run inside the passenger fender to hide as much wiring as i could. i taped the whole shebang to look more original and it does look pretty good. i dont have any problems with the original harness but for the HEI, run a seperate hot wire to the fuseblock for a constant 12 volts

Re: Opinions on using original wiring harness in restoration
 

As long as the sheathing of the wire is intact you should be just fine, if it is brittle and cracking you are asking for trouble. The most important thing is to ensure the wiring is protected with a fuse at the battery and proper sized fuses in the fuse panel. Do not draw more than the factory intended and you won't have any problems. The wiring harnesses on these trucks is pretty light duty as there were few accessories back in the day.

Re: Opinions on using original wiring harness in restoration
 

If the original harness looks great then reuse it. If any brittle wires or corrosion that has "climbed" under any insulation you can replace those areas.

If for whatever reason you need to replace it... companies like American Auto Wire and M&H Wire Fabricators make no kidding plug and play factory correct wiring harnesses. All the correct clips, tabs, mounts, plugs and they come with new plastic wire harness channels. No one would ever know that you didn't recondition your old harness with these kits.

I used some from M&H for my 1972 GMC and even opted for the HEI wire drop. I kept my external regulator as well. All looks completely stock.

Gary

Re: Opinions on using original wiring harness in restoration
 

The harness on my '67 is in remarkably good condition for its age too. When I unwrapped the engine bay harness recently to swap the distributor wire to run an HEI I was surprised to see the wire insulation was in good condition. Under my dash the wiring is still nice too.

Re: Opinions on using original wiring harness in restoration
 

One thing I would add... I used aftermarket. (My original was in pretty bad shape).
If your truck is mostly stock/original then a stock harness makes sense.

If you're adding elec radiator fans, elec windows, power seats, HEI ignition, a latemodel 3 wire alternator, LED lighting, electronic dash gauges, or any other major electrical changes, I would go aftermarket. If you're only changing one or two of these things, it's not so bad. If you're upgrading several things, aftermarket is the only way to go.

The other thing I like is the newer style fuses, I guess the old ones work, but they are sometimes difficult to remove and replace.

Re: Opinions on using original wiring harness in restoration
 

I thought mine was in decent shape until I removed it from the truck. Found a few spots that were a fire waiting to happen. I'm spending a butt load of cash to restore this truck and figured I didn't want to risk burning it up to save 500 bucks.

Check it over real good it may not be as good as you think. Nothing wrong with reusing a wire harness that's in good condition but these are 45 years old and most will not be in good shape.