Change in voltage

When I was a kid my older friend used a piece of plywood and tacked up his 1970 Truck harness . I helped him unravel all the tape and he systematically replaced each wire and terminal . Then rewrapped it . Looked similar to this. It wasn't really bad . He just took his time and did it here and there until he was finished.

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That’s really smart. I was about to pull the entire harness and use a 6’ work table, but finally found the final(hopefully. Lol) issue. I’m going to save this pic though. When I change my engine out, I’m going to go through the wiring again and if I don’t buy a new engine harness, this pic will be helpful. Thank you!