Which generation Efi ? OBD1 or 2? Can't decide

I'm in the same boat! I just bought a low mile 5.9 with all of the under hood wiring and ECU from a 98 3500 straight drive truck. I don't want to sink more into a harness than what I have in the 88 D100 that it's going into. I'm capable of modifying the harness myself, and would be glad to pay someone like Hotwire or ? to give me a wiring diagram of how to do it. Maybe I just haven't tried hard enough yet. I'm going to look on Alldata to see if I can find a wiring diagram for the harness, and see if I can cipher it out.