TKO600&Moser12bolt do I need to shim to get proper pinion angle for 69 bird?

[RBR]

I raised the rear end and it seemed to help. Now I'm thinking that the motor I'm running is prone to vibrate at higher RPM's. I have an 85 and older style GM crate motor from mexico. I've been told that it is the nature of the best for this type of motor. I'm still in the learning curve! Fixed the rack and pinion, was able to just put a new tie rod end on it.