The fuel sending unit must be a 90 ohm unit. It obviously is designed for use in a tank that the fuel sending unit has one side grounded and the other side going to the gauge. I looked at the instructions online and they're really simple looking. Now if only someone had a wiring schematic for you for the fuel tank sending unit. You could always drop the tank and check it out for yourself but that's just too much work. Got a salvage yard handy somewhere close to you? Maybe you can find a vehicle there and compare what's going on in one of their tanks to keep you from dropping the tank or removing the bed so you can figure out the wiring in yours. If I had not sold my 98 LS1 fuel module I would be able to see what was going on in there.