Swapping bodies on cars, need question answered.?

Okay, so I was wondering if it is possible to swap the body of one car onto another. For example.. If I decided to buy some old car in bad condition (let's say an old Ford or something) and fixed it up, would I be able to buy a body kit for a Dodge Challenger and just put it on without addition hassle beyond the manual labor? Or would I have to buy some extra special things? I'm not a car expert but my buddy is and he'd love to help me fix up a car. Thanks! Please include important details!