I have crawled under an HPOF(Historicaly Preserved Original Features) 1953 Chevy Truck at Hershey and noted that the insides of the fenders were body color (but it was a Black Truck so that does not really answer your question LOL). Actually, I understand that they were all body color on both sides. I am considering applying a "rock guard" coat inside the fenders with the "body" color top coat over it (this is a driver).
Terry
1953 1/2 ton