yeah... the OEM 4:10 torsen from any 94+ Miata will fit. If you are lookign to have slightly taller gears , get s LSD from a 99+ Miata with a 6spd tranny, the final drive is 3:90. All 5spd cars with LSD have 4:10 rears (excepts 90-93 which had VLSD with 4:30).

94-95 and 96-97 torsens differ slightly, the later ones are a little bit better in the sense they have better lockup. 99-00 used a Bosch made unit, which got put into the 04-05 Mazdaspeed Miatas.

Make sure you also get the axles from the right car too.. there are some slight differences in the axles.. but i dont know what they are.. MazMart would though.

my 99 came with a 4:30 open diff and i put in the LSD that was in my 96... its got over 200,000 mi on it and it runs jsut fine.. only change the oil in it now and then.