Gas tank from '53-'54 Chevy car fits great under the bed of the 1/2 ton pick up. It's mounted in the area where the original spare tire would be. The filler neck comes out on the driver side rear fender. Capacity is 16 gallons. You will have to make up a 1.5" dia. elbow (go to a muffler shop for this) to connect the filler neck to the inlet neck on the tank. For a filler neck you can use the '53-'54 Chevy car , or what I did was use the neck off a 1990 Caddy fleetwood tank. I used a gas filler door off a 1986 Buick LaSabre and welded it into the fender. Or you can buy all this stuff from Hagan's and spent the big bucks. I like the boneyard stuff that can fabricate to fit my needs and budget.