i tried putting gas in my rear tank and it would not take any. i cleaned the vacumm line on top of it and removed the filler hose and found out that the tank was full. i put the switch to the rear tank position but it doesnt take any from ther(also my fuel gauge is broken). could i need a new switch?

 

You may need to replace the solenoid that swaps the tanks. It's mounted under the truck. Follow the fuel line from the tank until you come to it.

 

do you knowhow much or how hard that is to do?

 

is the solenoid where the 2 lines from each tank go into? after that there is a another thing that there is a fuel line in and out , that has wires going to it? also i looked in the fuse box and saw that there is a space for a auxillary tank selector, there is a line side but no load side, is the terminal missing?