Although, I absolutely don't believe in doing such things, but just for my knowledge what is it all about and how it is done? Each body has a VIN plate on which vehicle model number, chassis number, axle and transmission numbers and plant numbers are engraved. If you put the body of other vehicle on the chassis of another vehicle, it will surely mismatch. But these MRA and Police Lab people don't look at the VIN plate at all. They only check/test the chassis number from the chassis and the same on auction or registration documents and engine number. People are caught because VIN plates are tempered or what? I have a personal experience of registering an army auctioned FJ40 last year in Rwp. Both, Police Lab and MRA people didn't look at the VIN plate at all.
And what is FRP Body? FRP = Fibreglass Reinforced Panel???