M3 LSD will fit straight into your car

M3 Evo LSD will not as it has a bigger case and the output flanges are diferent.

I looked at many LSD options when I was putting together a conversion on my E39 540i Sport and ended up using the M3 Evo LSD/case with an M5 cover and shortened the propshaft by 15mm - Everything else was identical to what I needed apart from the gear ratio was slightly higher so acceleration was improved at the loss of top speed (but the speed lost was past the 155 limiter so never a problem in reality)

I did a massive writeup on the BMW5 forum about it, but the whole shabang cost me £500 to do as I was lucky enough to get an M3 evo diff from a breakers for the princley sum of £200