318is with 3.91 LSD

[nroye30]

While looking around my newly acquired e30 i noticed that someone had swapped a 3.91 diff into it. Any way to tell what it was originally from?

[mtech325]

Assuming it's a US car, here's a few possibilities:

If it's a small case, it may have come from an m10 powered 318i e30.

If it's a medium case viscous LSD, then it's out of a manual 325ix e30.

If it's a medium case clutch LSD, then it came out of a e24 635 automatic car (possibly an e28?) and the cover has been swapped to an e30 version.

I hope this helps you get started!

[fresh_TD]

e21s also came with small case S3.91 diffs