[hatzie]

Originally Posted by rodstored-72

hatzie, I tried to skim through and find out, but can you tell "us" again which tank (side) is the main tank? and which is the aux. tank? I am trying to do this on my '86 LS swap now... still!

thanks!!!

1981-1991 tank switches are marked RH & LH. The tank you use as your "main" tank is up to you.
Why? The motorized valve stays where it comes to rest and doesn't change again til you select the opposite tank. Select the RH tank with the valve plugged in and hook the RH tank hoses to the side that's open through the valve. Or select the LH tank and do it that way.

AUX and MAIN are really only meaningful with the 1980 and prior solenoid type valves. AUX is the tank selected in the powered valve position MAIN is the unpowered position. AUX is entirely dependent on the way the valve was hooked up by the last guy that was working on it. I've seen LH AUX and RH AUX tanks.
I believe the 1973-1980 primary tank was the LH tank but don't quote me on that. My single tank 1974 had the fuel door on the LH side of the bed. Yes the fuel door bed came off a later truck. No I don't know whether one of the previous five owners moved the tank from the RH to the LH side of the truck.