i have a 77 630csi and i had to get a new driveshaft for it and flex joint got the drive shaft from bavarian auto recyclers it had a new center bearing and has been reconditioned. the problem i am havin is its coming up a inch short in the rear so i cant bolt it up to the diff. i have tried sliding the centerbearin bolts and they are set in place and will not give me any room. i also saw that there is threads on the shaft after the center bearing going to the diff but when i spin the ring around the threads it does nothing