You'll need to heat the fasteners with a welding torch. EXTREME caution should be used around a fuel tank. If you don't have acces to a torch or are not completely familiar with using one, you should find a local mechanic who will loosen the fasteners for you. Another popular methode is to remove the cargo box instead. This way you run less of a risk of damaging the fuel lines. One way I have done this, was to cut an acces hole in the bed of the truck just over the fuel pump, and fabricate a patch afterwards. A four inch hand grinder with a cut off wheel works good. But agin,be cautious cutting and grinding near fuel tanks. You will need a new o-ring for the tank unit. They're always swollen when you remove them, and won't fit back. They're only a few dollars. Good luck.