So onto another problem I have with my 78 f100 I can't find the switch to change between tanks I keep looking online and nobody has a clear answer and I can't seem to find it if anybody knows where this might be a location would be greatly appreciated!

 

Mine is on the right side of the heater controls on the dash. I have a '77 F150.

 

Was about to say mine is to the right of the instrument cluster, Next to the a/c. But should be in the same general area. I have a 78 F-150

 

The switcher is on the right side of the Heat and A/C controls, it looks like the the fan speed selector and says "Main" on top and "Aux" on bottom.

 

My 73 is RH side of heater controls, its for gauges only, my fuel valve is manual and is located on floor between seat and door.

 

And what Bill said is what was done to mine, it had a manual valve installed on it to switch the tanks.