In the trunk, behind a carpet covered board at the back that just pulls away. The sending unit is at the top of the tank in the middle. There is a plug with wires attached. When you remove the collar, be careful with the large o-ring. You may get away with reusing it. You have to lift the sending unit up and then tilt toward you to remove and clear the bottom of the speaker deck. Sometimes, as was the case with my '91, the deck is too low and you will have to go to plan B which is to pull the tank. If that is the case, I would get a new sending unit altogether and not waste the effort of doing what is really just a bandaid for now. Pulling the tank is a bear of a job and one you only want to do once. If you are lucky and it comes right out, it pretty easy to fix.