Has anyone swapped a newer 4t65e with an older vehicle using its PCM?
I Need a transmission harness wiring diagram, 20-pin for a 2000 Monte Carlo SS 3.8L. I can only find 03+. For the 00 engine side I need it for a 19-pin, and if possible a 17-pin diagram for the 04 trans side.

I am in the midst of swapping out the old 2000 for an 03+, which is a refirbushed 2004 transmission. The problem I have is getting the old harness to work with the new one. As in, the old pin plug to work onto the newer on the transmission. The 2000 Monte carlo has 19 pin out of 20, only the bottom corner (W) not being used, and the 04 trans has 17 pin with only the middle 3 (NPR) not used.

What is W for? I can only find it may be for a Park Neutral Safety Switch signal.
I found some information about either swapping or jumping NPR with FGH and ground K. Is that all?
Do I swap pins or splice together? A diagram would help.