tl:dr

Do a burn out and if there are 11s then you have a torsen.

 

for 99-00 NBs you apparently can look at the door jamb and find an "NCxx" number.

 

Ok can anyone confirm that if you look thru the rearend where the axle hubs push in if there is a bar its open if no bar its torsen. I have a junk yard with a 95 5 speed rearend but no vin. Car was crushed.

I need some way of finding out. I know with my open 1.6 diff there is a bar with the torsen rear end for 90-93 there is no bar so is the same true of 1.8 rear diffs.

 

Here is a pic. There looks to be some sort of rubber dampener at the pinion. Is that right or is that for automatics?

 

I believe it was states in this thread that there where only open diffs for 89-93 cars. Also, don't torsens have different ratios then a open diff? If you know the ratio of the open diff and of the torsen, you can figure out which one it is.

 

the torsen in the 90-93 cars is different and not as effective but it was avail.
Torsen and open have same ratio. I found a post on id'ing them. i will post it over here. From that post the rubber thingy is a good sign and if it does not have a bar it is prob torsen.

 

http://www.miata.net/garage/diffguide/index.html

 

Miata.net is a great resource for this kind of stuff.
BTW, you can edit your posts once you've posted them to add information so you don't have to make multiple posts.

 

The viscous was the LSD in the 90-93's.