body change

I have 2 p/u's, both are 92' 1500's, long box, s/c, 1 is a 4x4 with a rotten body, and the other is 2 wheel drive with a GREAT body, how hard would it be to put the body on the 4x4, and the 4x4 is a 1500 but how can i tell if its a heavy duty chassic. On the 4x4 i need some new parts but cant find them, 1-gas tank cross member (cross member holds the front of the tank), 2-shock mounts (top of the shock to the frame)

What's s/c?

The only difference should be the hole in the floor for the shifter. If you have the tools and some friends to help transfer the bodies, it shouldn't be that hard.

Have you checked at salvage yards for the parts?

i want to get new ones, i figure if im going to remove the hole body, which is garbage from the 4x4, then i might as well sand blast the frame and repaint it while im at it, but for the parts i need VERY truck i've seen have the some problem, but that could be because of where i live. i want to do the frame right the first time cause i intend on putting a 6" lift (if i can find one at a reasonable price.

You may want to try looking for fabrication shops in your area. You may not get an exact replica, but I don't think you'll find a new OEM part. Calling salvage yards in the southern US may have good results. You'll want to try further south than Iowa, we have the same rust problems here.