2003 Jeep Grand Cherokee body swap?

[newracer]

Back up...

Jeep Grand Cherokee's are uni-body vehicles. The body is the frame. You can't swap the "body".

4x4 to 4x2 does not necessarily prevent a motor swap. If the motor is the same (likely) it's a straight drop in.

Swapping the whole drivetrain in is also an option, but may require some "custom" work for the 4wd shifter.

This. I'd swap the entire drive train from the 4x4 to the 4x2. The only difficulty I can think of is you might need to swap the computer as well.