Tool Box-Fuel Tank Combo

I had this installed, wasn't cheap, but a flip of the switch and also the gauge reads the tank you using at the time. Of course you probably need to be close to Dallas!

http://www.customtrucks.net/customtrucks/

I installed my gravity feed RDS 80 gallon tank myself.:C

I had a gravity tank in my 07 GMC and it would set the CE light all the time. The computer couldn't figure out how i could drive 350 miles and still have a full tank of fuel.
In the 13 I went the Transfer Flow route. Yes it is more $$$...but well worth it in my opinion. The best part is that should I end up with a different truck, it can be moved over fairly cheap.

Are you looking for two of them?

http://auxtank.com/auxtank/home.asp

Transfer Flow may not be the cheapest, but mine has been working fine since it was first installed in 02.

Northern Tool has a big selection of gravity feed. Mine is a 50 gallon toolbox tank combo. Gravity feed has worked flawlessly.

I think this is my aux tank I bought.