there are fiew different driveshafts...
1. 4cil engine with 4 speed gearbox
2. 4cil engine with 5 speed gearbox also sport gearbox
3. 4cil engine with automatic gearbox
4. 6cil engine with 4 speed gearbox
5. 6cil engine with 5 speed gearbox also sport gearbox
6. 6cil engine with automatic gearbox
actual difference is in front part of driveshaft and if it haves 3 or 4 bolts to attach to gearbox
and difference is if it is early or late model...
http://bmwfans.info/parts/catalog/E21/S ... ive_shaft/