Cylinder Lock Issues

[BAMM71]

I've got a 71 C10 that the ignition key is a PITA. It just doesn't want to play nice and takes a couple gentle proddings to finally get home. Once there, turns over like a dream.

I ordered a new lock cylinder, removed old one, put in the new one and it won't turn to the right to click in place. Well, I figured I may have ordered the wrong cylinder..they're 5-10 bucks depending on the shop. Original was from LMC and then I ordered another from RockAuto (ACDelco) and the same issue. Put the old cylinder in and it's good to go. Any ideas where I've gone wrong? It's not the end of the world but would be nice to be able to just jump in and go!