Good responses here thank you! Im not sure what the doors are tied into as I did not build the truck from the ground up, nor have I had the interior apart to see. They are however hung with some pretty heavy hinges in the back that must be tied into some steel somewhere as they are very sturdy and do not move at all. There are 2 hinges for each door as well. There is also metal bracing tied through the door and wood structure inside from side to side to strenghten the door up.

As for those rubber stops in your door sill could you post some pictures of those installed? I have nothing like that, its kind of what I had imagined.

I do have the deadbolt installed in the front with the suicide doors, its pretty solid as well. I need some sort of weather stripping or stop as was said here as I have nothing currently.