Okay. I'm looking to make one of these for myself, and I think I understand what's going on here. I have my PCM plug, and OBD2 port in hand. The rest I will get next time I'm by a radio shack.

So here's my question;
All my wires and numbers for the PCM plug jive except #56 (ground). There's no lead from #56. Safe to assume I'm okay without it, because #56 and #60 run together to ground? FWIW, I did get the PCM plug from a GP.