Differential housing compatibility
 

Been searching for a while but still can't find the answer...I have a 90 model with the small 1.6 ldiff. Just picked up a 1.8l, 4.1:1 Torsen diff out of a 96 model with intentions of piecing together everything I need for a complete diff swap. I am looking for a 1.8l diff housing and I know the 94-97 will work with what I am trying to do. Question is will a 99-05 differential housing work with my 96 diff and then bolt into my 90 model? Or, am I limited to using the housings from the 94-97 model years?

All 1.8L housings are the same. There might be small differences but nothing that will prevent you from using any 1.8L diff component.

Thanks for the reply. I found an RX-7 rear housing for $100...Is there any advantage or disadvantage in using one of these over a std 1.8 housing?

Yes, the N/A Rx7 housing is stronger (no break-point for crash testing). You will need to use Miata bushings, though.

Thanks...Will the bushings out of the 1.6 diff housing work or will I need to source some 1.8 bushings?

The odds of you getting them out without damaging them is about zero. Pick up some Energy Suspension polyurethane diff bushings.

Someone correct me if I'm wrong but I believe the bushings for the 1.6 and 1.8 are the same. You can pick some up here:

http://949racing.com/diff-mount-bushings-miata.aspx

Diff bushings should be the same between '90-'05.