Align doors

[Rc4mike]

Wondering if anyone has had this same problem. I have a 59 apache that I'm trying to fit my doors. I have around 1/2" gap at front of door near window and 1/2" gap at rear of door. Was about to start filling gap when I realized my problem is that my cab has spread. I used a tie down strap to squeeze the cab and close the door gaps. Got them close to how they should be then released strap and it spread again. I'm getting about 1/2" movement when compressing the door opening.

Anyone seen this before ? What's best way to fix this?