The filler neck (plastic or steel) and the grommet can be replaced without removing the tank. It is tricky, cumbersome and can be a bit frustrating, buy if you follow the proper sequence of loosening the two hose clamps on the rubber hose connecting the tank neck to the filler neck. I left the cap on the filler neck in order to get a good grip and twisted the filler neck out with the cap attached. Now cut out the old filler neck grommet. The rubber hose will now slide out the hole in the cab.
Replacing these parts requires the sequence to change a bit. Start by inserting the rubber hose with the two hose clamps. Tighten the hose clamp at the tank neck. Leave the other loose until the filler neck is installed and set at the proper clearance. Now lub and install the filler neck grommet. Make sure it is properly seated and indexed with the offset in the opening relative to the offset in the grommet. Now insert the filler neck through the grommet into the rubber hose. Press the filler neck into the hose to the proper depth to allow the cap to be installed and leave a minimun amount of filler neck exposed. Complete the installation by tightening the second hose clamp and installing the fuel cap.
Best of luck with your filler neck woes.
