When u do the fuel filters there are the 2 on the side of the motor and the primary is under the right fender area, U are supposed to be letting that one drain now and again to see if there is any water in there, and U may find the pet cock is cloged/rusted up and needs to come off to make it work, that is common, that filter is a shorty, the other 2 are the same,all the diameters are the same though. u will find when U buy those they may have a different diameter hole in the center from the ones in the truck , do not worry they work just fine, the Military uses both sizes all the time...when they go on they center right up, just an FYI, for the next job...
