What does it take to add an additional fuel tank/cell to a truck??? As in, what does it cost, how difficult is it to do, where is the best place to get it done, etc??...I'm asking b/c I looked at a '70 F-100 in San Antone this past weekend that I'm considering buying, however the fuel tank in it is only 12 gallons or so, and, apparently if I invest in the truck, I'm going to have to look into a method of carrying more gas, and I'd like to have an idea beforehand....I know a few in the club have done this already (Scott?)?