Seeking some info on wiring harness

[Clatterville trolley]

I bought three tubs of wiring harness' in a whole load of other 67-72 parts. That was a while back and I am just now going through them to see if any of it is usable.

Thus, I now have some basic questions about harness construction. I have an assembly manual and have looked at those wiring diagrams and I purchased a wiring booklet from LMC only to realize that the same information was in the assemble manual

I see in the diagrams a wire that is called 'resistor wire' is that just a small wire that will melt quickly if something goes wrong or does it have a 'resistor' linked into the wire?

Also all of the wiring harness I have at least 2 or 3 wires cut off. I was thinking if I unwrapped a couple of the more complete ones and robbed the needed wires out of some of the extras I could come out with a usable complete harness.

I have inspected all of the harness and have found some pretty wild "adjustments" to the original harness. I have a couple of pictures that I will post after I get the photos loaded.

Is it smart to use the old wiring - 50 years old - or is it just more realistic to bite the bullet and get a new harness??

I have learned a lot just reading some of the threads over the last few days. Look forward to maybe contributing some myself. Really I have learned a lot just going over the old harness about what is in what harness and where it is placed on/in truck body.

Thanks for any insight! Jay