Many interior parts from a pick-up will fit your truck as well as some sheet metal and other misc parts.
Also when searching for the Running Boards that you have mentioned above, there should be a difference between the wide fender ones and the narrow fender ones, like there is on the '60 to '66 style trucks (narrow fenders means narrow running boards). I haven't seen a picture of your truck, but your 5500 will most likely have the narrow fenders.
Bill
