Single tank to Dual tank
 

Hey everyone. I have a 1978 K20 and was looking for some information on adding a fuel tank to a single fuel tank truck. I have a bed from a dual tank truck and would like to add another 20 gallon fuel tank. The truck does not have any of the wiring, switch, or transfer valve. I would like to stick with the factory switch and transfer valve if possible. Any information from someone who has already done this would be much appreciated. Thanks

Re: Single tank to Dual tank
 

You should be able to install the 1981-1991 dual tank system.
The valves for the 1973-1980 system are made of unobtainium now.

The filler necks are different diameters after 1980. If the bed is from an 81-91 truck with the 81+ filler necks get tanks that mate with the fillers.

The dual tank theory of operation thread should help.
Post #2 is the 81-91 system. Ignore the TBI fuel pump info.
http://67-72chevytrucks.com/vboard/s...d.php?t=754061