Is there anything different engine wise in the Bullitt Mustang? Or is it just the body?

 

Assuming you're talking about the original, there is no real difference in either the body or the engine for the Bullitt cars (there were two, iirc). They were S-code (390)fastbacks with all of the trim and grille ornamentremoved, with 15" Torque Thrusts, stiffer springs, and I believe Koni shocks.