I know some guys won't agree but I installed all new latches and strikers on my AD and they work just fine.
When you close your door without the mechanism, does everything line up? If it does I can't imagine why you're having the problems you're having. Those parts are pretty much in a fixed location because there no up/down slop to adjust.
Get
SERVICING CHEVROLET TRUCK CABS reprint, I learned a LOT about doors from that little pamphlet.
