I remeber hearing something about the Subaru Legacy's lsd fitting the S12? I'm not sure which year(most likely the same years as the S12). Is that true? Hope I could be some help.

There are 2 types of Subaru diff. The R160 and the R180.

Both will bolt to the s12 cross member, but the hardest issue is the shafts. I have an R160 diff at home, and the shafts are thinner and use a smaller CV design, so it would require some pro work to match the shafts. The shafts would definitely need to be longer due to the narrower case.

Not sure what shafts the R180 has, but if they were the same as the S12, then it would be safe to assume the shafts would be easier to match.

You also need to consider that the R160 diff is only designed for 100bhp at the rear wheels. The R180 was fitted to the more powerful models like the 22B with a mechanical LSD not viscous. This may well handle the power though.

What about the Z32 LSD? Is it VLSD or clutch-type? I assume it's also a R200, right? Or is there too much crap going on with the axles?

I guess the Z32 diffs are viscous.

But in answer to your question a Z32 TT diff won't fit. Its an R230.

The Z32 NA one would be useable as its an R200. You'd need the shafts as well.

yeahh:D ok now i understand, thanks!! I think i'm going to search for a s13 lsd diff and try the conversion.

Is there a way you can see you are dealing with a lsd diff instead of a normal diff with the s13?

Well you have to look hard for this sticker on the left hand side of the diff:
http://img.photobucket.com/albums/v210/30psi/S13LSD.jpg

Coming back to s13/s14 vlsd. So to make the conversation will the s14 shaft and etc. fit? Or will i need another s13 diff, for the few internal parts?

And i supose ten subaru r180 diff would be next to imposible to find

No just use the S14 shafts, and internals.

The R180 diff is probably easy to get. But its probably harder to deal with the shafts. Also, you'd need to check the ratio of this diff.