Starter works fine when not bolted in the truck, when I bolt it in all I get is a click

Starter looks to tight to flywheel.

If the above doesnt help,take a few plugs out and turn the engine over by hand.If it doesnt turn something is jammed,or engine is siezed

The weird part is I tried shims and they didn't do anything, starter didn't have shims when I took it out. I can turn the flywheel by hand and the starter retracts by itself

If any of the wires in the starting circut are corroded it could imped the power enough to hinder it under load

did you ever have the original starter? Does it match the new one? the more I look at it it seems like the wrong one?

I put new wiring on it and the starter works on it because I only took it out to put new wiring to the battery on it

Great! Thanks for reporting back to help others

My truck ended up needing an extra ground wire (from engine to frame) only had one from battery to frame. Works good now

Right arm man, glad you got it fingered out! Stock location for that is to the frame right behind the steering gear I believe