I was wondering first off how big is the gas tank on a chevy 2500 3/4 ton long bed?

[Jas]

I was just wondering how big the tank was, i have seen 26 gallon tanks and 34 gallon tanks but i am not sure which mine has. And my gas gauge goes nuts when the truck is turned on, just spins around and some times flip back and forth. The chevy place here where i live says i need a new tank, but they are not a place i would advise taking my truck from what i have seen (no offence to any deals or workers out there) so i just wanted to make sure it is the tank and the gauge cluster.

[alvarz]

20 gallons

[Cody M]

it is NOT a 20, i would assume it is the 34 gal, but its hard to say for sure......it is def. the cluster gauge and not the tank, there is a most likely a loose connection along the wiring harness somewhere and it is grounding its self out and not reading correctly, or it could be the sensor in the tank, whichever it is is not to big a deal, but i would not attempt to replace a cluster gauge set up on your own with out experience doing it