Yes, I have an '03 and '04 pump both in my truck. (I also go by Frostking) I used just an '04 fuel pump / basket for a few years. The only modification needed to use a newer pump on the '03 is to trim 1/8" around the collar where it seals onto the fuel tank and re-use the '03 o-ring and collar. As mentioned already, the fuel regulator on the '04 is set to 58 psi instead of 48 psi ('03) Some say the regulator itself can be swapped, but I tried everything and couldn't get either regulator to come off the fuel baskets. Without tuning, an '03 will run 10% richer having 58 psi feeding it.