Originally Posted by GeorgeSmooth
You can search on the M3post. Dinan, Evosport, diffsonline and the OEM 3.15 that I can think of from the top of my head.
where to find the OEM 3.15 one at a reasonable price?
as far as I understood the single parts aren't available by BMW, only the complete diff. Unfortunatelly I found only a normal 3.85 M3 6MT diff at the scrap complete with all the subframe, harms, brakes and half shafts..