8-3/4 sure grip unit

I have the same unit in my 67 Dart. I have had it apart twice trying to see why it goes clunk clunk. I don't see any way to line up the splines without using the axles. Be carefull to not over tighten the bolts. I had three snap using specs I got from a magazine. I have found an open diff. for $75 and am settin my 489 sure grip aside.
George