pinion angle after rear lowering

[dhamilton62]

Just wondering what you guys have done to get the correct pinion angle after lowering your trucks. The P.O lowered my truck in the rear what looks like 5". He did it with just drop coils and that's it. I'm thinking that I need to fix that situation with using lowering blocks and perhaps shims to correct the angle? If so, what would you guys suggest I should do for a 1962 c10? Would having a incorrect pinion angle make the truck vibrate at highway speeds? Thanks!