you might ask this in the m-series category......
but all i know is the 95 has OBD1 and the 96 up had OBD2. for the difference between the two you can do a search here on the forums and get all the info you would need. I thought all M3's had limited slip but im not sure.
Mods: Tint, Euro Tails, Smoked corners and Side Markers, E46 Style Shadow Grill, 18" M3 Replicas, M3 Exhaust, Low Beam Silver Stars