Riddle me this: small-case 3.91 LSD diff - what the hell did it come on?

[84driver]

E30. I have one too

[irish44j]

According to realoem.com, a 3.91 limited slip was used on 318i cars with manual transmissions from 1983-1988 (part number 33101211466).

excellent, thanks. Don't know why I didn't think to look there. Duh.