Also posted this in the '99-03 section.

My brother has had a '99 F350 cc 7.3 turbo 6 spd for 6 months now. It runs great and he's real pleased with the power and towing. It appears completely stock. A friend of the original owner told him it had a 'performance chip' in it. My brother has been shopping for a chip or tuner, but would hate to pay for something he already has, and not gain anything. Is there any way to tell if something has been done? Would a professional scan tool be able to tell if the pcm has been reprogrammed? Is there any way to know? I appreciate any help.

Marty

 

If it has a chip you'll see the chip module sticking out of the back of the computer box.