Using aux gas tank as main gas tank

[JerryIndy2112]

I have a '71, GMC, 1 ton. It is the custom camper version. It was sold at dealership with a camper on it. It has the main fuel tank behind the seat. It also has a fuel tank under the bed, drivers side. Has anyone used the auxiliary tank as a main and removed the one behind the seat? Fuel tank sender to see fuel level? Replace aux with new and better tank with a sender? I am planning right now. But would love the extra space. I do not have key to aux fuel door. Would love to weld in a square body door to open and fuel. I have picture below. Give me your thoughts and experience.

[BigBird05]

The first thing I did was get a patch pnl and fuel door off of a 73. They are still around hear.

[JerryIndy2112]

My question is does any one make a fuel level sending unit for the auxiliary tank?

[special-K]

Yes, my truck came with two auxiliary tanks. I have a switch on the dash for reading level in each tank: Left - Main - Right.

What room do you gain? The tank is installed in the extra unusable space behind the seat, a great design. Aux tanks were installed to give extra capacity over the factory 21 gal. and you want to drop that down to 8-10 gal.

[JerryIndy2112]

Well, I thought the auxiliary tank was bigger than 8 to 10 gallons the owner said it hasn't been used in decades. I would like to put speakers behind the seat.

[BigBird05]

I am going to mount the gas tank back wear the spare tire used to be. Then run the filler pipe up to the left hand box side and use the fuel filler door off of the 73. I like the idea of getting the gas tank out of the cab.

[special-K]

It's funny how people holler about doors cut for speakers to be installed where they are in newer trucks, but they'll cut the bedside for a fuel tank filler

Originally Posted by BigBird05

I am going to mount the gas tank back wear the spare tire used to be. Then run the filler pipe up to the left hand box side and use the fuel filler door off of the 73. I like the idea of getting the gas tank out of the cab.

Hasn't bothered me being in the cab after driving these trucks since '73, but to each his own on all of this. Just saying there is no cause for concern. It's safer there than up under the truck and in the back where people get rear ended

Have you thought about where the spare will go?

[mrein3]

Originally Posted by JerryIndy2112

My question is does any one make a fuel level sending unit for the auxiliary tank?

Years ago I bought a generic fuel sending unit from JC Whitney. It came with a gauge. I mounted the gauge knee-knocker style and love knowing what is in the aux tank. The previous owner simply started on that tank and ran it until it was dry. Then he always knew what was in there - some or none.

[jkeady]

My truck has a dealer-installed saddle tank. I bought a universal sending unit from summit that had an ohm range for the factory gauge. Took the tine to remove the old manual valve and replace it with an electrically-switched valve. Wired it all up to an on-on toggle under the dash.

My aux tank is only about 12 gallons. Definitely more of a range extender, I’d find it pretty annoying to use it as the main tank (I still use the in-cab tank).