hey don if its for ur chevy p/u, ya may want to looka at a fullsize blazer or suburban tank. they come in several sizes up to 40 gal, & w/a little frame trimming they fit nicely inside the fame rails in the rear. i have used them several times on the 48-54 chevy p/u's that i have taken the bomb out from behind the seat. you do have to move a brace to the rear of the truck & then fab up another for the front of the tank so ya can strap it in.hope this helps ya. or if ya want inside the frame rails look at a S10 tank but they are only up to 20gallons..joe