Probably a symptom of a bigger problem, possibility the flexibility of the cab. I don't think it should be that flexible that changing the cab mounts would throw the doors out of alignment. How are the joints between the rockers and A and B pillars.

Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.