Which vehicles 87 and up share the same harness to ours that i could pull from a scrap yard? im not quite ready to rewire my truck, but should be there by summer. painless offers a harness, but i'd have to switch to MAF, which i do not wish to do. only wiring changes i'm looking to make are to alternator wiring to upgrade to the 3G. just realized that i should check interchange thread as i haven't been here in a while.
A wiring harness is made in several sections - you might find an identical section on another vehicle type, but it's not likely. Even 2 '86 5.0L Flaresides will have many wiring differences; going to '87, there were several substantial changes to the wiring, so the chances of even 1 section matching your '86 are very low. It's much easier to just repair what you have, unless it's burned or severely degraded. If you have to change any major section (like the dash, engine bay, or frame) to one from a different donor vehicle, it's better to change EVERYTHING from that same donor.
The alternator section is an exception - it's a standalone system that can be easily swapped from virtually any donor to match the alternator you choose.