I rebuilt my twelve bolt posi with new spider gears, new posi plates and new shim kit from Tom's Differentials.
http://www.tomsdifferentials.com/
I watch Tom's you tube video (parts 1&2) before the assembly and it assembled just fine.
https://www.youtube.com/watch?v=CGq15JBBUQw
The twelve bolt has 500 miles on it now and it clicks and sometimes catches when turning .
I have put in two bottles of posi additive and it helps but did not cure my problem.
The shims are too tight on the posi plates and creating the problem. It is not a terrible problem but annoying.
Will it get better with more miles on it or should I change shims?