The cam timing is unique on the 96. it was tuned for more low end grunt, which may make the 96 the most desirable setup for everyday city driving.
nit pick: while the 96 does support the OBD-ii port, it is still not yet a full OBD-ii protocol. Kinda like obd-1.5..... the '97s (FGY33) were full obd-ii, but also still had the consult-1 interface.
i believe the head castings were the same from 94-96.
all 90-96 blocks are the same, balancers etc may be different.