Everything 96 or newer is OBDII
Oops! I must of been half asleep. I meant, that in '98 the PCM went through some changes from 96-97. For example the knock sensor was moved from the PCM to the block making for faster scanning/detection rate. If u ask almost anyone that hacks their OBDII PCm they'll tell u that '98+ is better in terms of "scanning, re-writing, ect."
FYI: I have a '97 Grand Prix GT that I swapped the wiring to a '98 PCM (pretty much all of them...which there is 80 holes for wires to plug in but, not al are used, u get the point) Then had to add a few for the supercharged PCM sensor, (ex. boost bypass, MAP) I use a DHP(Digital HorsePower) PowerTunr Programmer. I can scan, tune, shut off codes, ect. Its an awsome program and VERY user friendly.
I've also swapped a Series II 3800 (s/c'ed) into my 'ol '96 GP. For that one, I used a '98 harness and PCM, then just cut & spliced the wires (20-40) at the firewall plug.
There's ALSO a guy that did a SeriesII 3800 swap into a Olds Cutlass '78-'8* I gotta find out if he used a RWD harness (which would make it so u could hook the engine to a 4L60trans) or if he shut off all the trans codes and ran a TH350 or the such.