Hi
My '48 GMC's tank had water in it for a couple of years before I got it.
I put the tank which is located under the bed on passenger side.
Did all the above, no replacement tanks available.
1st washed it out with clean gas, then added more gas with 3/4 inch crushed rock. rolled and shuck it for about and hour. Pour out the mess, wash with lacquer thinner, then used Muratic Acid to prepare the tank, flushed with soda and water serveral times, then plain water, then alcohol to dry it out. Then used about a quart of airplane tank sealer, it is FAA approved.
Been driving the truck for 6 years since I cleaned it, also added a new fuel line and fuel filter at tank end.
Good Luck
GMCPic
