Which model year manual transmissions will fit my 90SE?

 

89, 90, 91, 92, 93, 94.

92, 93, 94 VLSD trannys will require some more work (different hubs, half-shafts)

 

Tranny codes are as follows:

VG:
A/T: RE4F02A
M/T: RS5F50A

VE:
A/T: RE4FO4V
M/T: RS5F5OV

Both the VG and VE transmissions will work for your car but like lophix said the VE trannies willl require more work. Hope this helps