Here's a pretty good video a friend and me made about doing my wiring harness for my 55' LS 5.3L swap that I'm currently working on. It shows how to disassemble the 1999-2002 Chevy/GMC 4.8L 5.3L and 6.0L truck wiring harness, how to remove the unneeded wires for certain things, redo the grounds, and finally convert it to a 4 wire hookup and package it back into a nice harness.
Part 1:
Part 2:
Part 3: