Not that I am an authority, but I looked into it a little -
Without going any further (because I am not sure):
In the People's Republic of Kommiefornia you cannot install an older engine into a newer vehicle so SMOG would be an issue.
ECU
OBD2 in the 96, not in the 94
AFAIK - the output shaft on the 94/95 tcase is shorter than the '96/97 and the 96/97 year model is the "q" variant - which is supposed to have quieter gears.
Engine - 3.9 vs 4.0: (
Buick 215 Rover 3.5 Land Rover 4.0 and 4.6 differences)
- The 3.9 has the provisions like the 4.0/4.6 litre for the crossbolts but they have not been drilled.
- The 3.9 has the smaller main journals from the 3.5 while the 4.0 version has the same journals as the 4.6 litre.
- The 4.0 crank has a longer nose.
- The 3.9 has the concentric oil pump but coupled with standard distributor the 4.0 has a distributorless system and thus no hole for a distributor.
- The 4.0 uses longer rods, lighter and shorter pistons.
- The 3.9 had the 14CUX 'hotwire' fuel injection. The 4.0 has the Lucas 'GEMS' engine management system (latest see Bosch 5.2.1 Motronic)
- Because of the way the fueling and ignition is set up, the 4.0 has knock sensors and the 3.9 does not.
- the 4.0 puts out 186.4 bhp and the 3.9 puts out 190.4 bhp.
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I hope that is helpful, this is not a complete list of the differences.