Has anyone put a larger gas tank or a small sliptank aux. tank in their truck? I currently have an 18gal tank and can't go more than 250m on a tank.

The problem I see with an aux. tank is my truck is a regular cab short box, so I am unsure if there is enough room to put it under the truck.

Any suggestions would be helpfull. I don't mind taking out the spare tire rack underneith because it is to small for my spare anyway.

 

Sounds like you only have 1 factory tank - have you though about adding the second from a junkyard? You could get all the parts you need off a similarly-sized truck (so the tank fits in your chassis, but the lines & wiring could come from a longer truck) and make it all OE. That's what I always do - take a look at my sig link.