over here in malaysia, there are many shops, (commonly called as Half-cut shop here in Malaysia). These shops carry salvaged parts including complete car half-cuts, front or back. The parts usually come from various countries, so i dont know where did my gearbox come from.
my mechanic over here found me the gearbox from one of these shops. It was a 318IS halfcut (dont know where it originated from), so i just bought the gearbox from that halfcut seperately.. didnt buy the engine hahaha..
Yes, depending on what parts you get from a salvaged bimmer, this is what i think you should need to have :
1) gearbox - the transmission box, should come with everything intact inside such as clutches, flywheel, etc..
2) Properler shaft - a must, because ur auto shaft is different from the manual one
3) Rear Differential - also a must, if you dont change this, and remain your auto differential, (which i assume dat the final drive to be 4.45), you will have helluva extreme pick-up/torque but it will wear/tear ur engien faster as you will be revving to much. Imagine, the top speed of only 90mph on 5th gear!! So u must get this as well, the correct final drive should be around 3.45. (if u can get an LSD, that'll be better!)
4) Clutch Pedal, BRake Pedal and gearknob. (You wil be able to continue using your acclerator pedal) - but make sure they remove the kick-down switch and check that your car is own full throttle when pedal is fully pressed. (after the swap of course)
well, i guess thats what u need for a swap!..