have read through that tread below. conclusions seem to be only that the M variable differentials were changed/updated at some time during production from the E46 M3 to the E86 Z4M. the pics provided in that tread also showed some differences internally to both differentials (post 13)
http://www.zpost.com/forums/showthread.php?t=393888
would anyone know if the E46 4:10 ring and pinion from Turner motorsports install correctly to the Z4M differential?
thanks