I think this should be posted in the "Hybrids and Gamesharks" forum - you can g/s the non-[R] body onto normal cars, but for cars like the Escort Rally car, they cant be changed into the normal bodies as there is no bodycodes. Search the internet for more details
Exactly...about all you can do is code the body of an un-modded car onto an existing car. You can modify the bodies, and in some cases, the colors of the car with lots of codes, but the changes don't save to the memory card, and it's a real trial-and-error process (tending more towards "error").