Is there a link somewhere (or if someone wants to show off and spell it out for me:) ) of the differences between the 91, 92, 93, 94, 95, 96 G20s? (The fully independent suspension ones.) Kinda window shopping and figuring out which have what.

Check out www.g20.net
Do a search on that forum and get all your answers over there.
The basics:
The '91-'93 have the high port SR20DE and is OBD-I
The '94-'96 have the low port SR20DE and is OBD-II
The '93.5 shares parts between the two ranges.