My buddy owns a 72 Scamp with a 318. The car has a chrome gas cap that is a little scratched up and he was wanting to replace it. While at the Mopar Nationals 2 seperate vendors told him the chrome caps they were selling would not work on his 72 ? Can someone tell me what the difference is and what would be the proper cap for this car? What would occur if he wwas to have put the wrong one on ? Thanks in advance for any responses.