you can fix the old tank, or have it fixed, by de-rustig the inside, welding or soldering up any holes [including the ones that will appear after de-rusting], and using a 'sloshing' compound available from a number of suppliers to coat the inside
new tanks don't come with petcocks .... learn more about the configuration of the trucks before searching for parts - asking for something for a 3800 1T confuses the situation, most places list all the parts they have for these trucks as being for a 3100, and while some of your 'hard parts' like brakes and steering may be 1T specific, any size pickup has the same tank, and the tank is the same for a range of years - not sure about the AD series, but I'd expect 49-54 at least [Tim?] ....
check out the GM info pack, if you plan on keeping the truck, get a shop manual and the 47-54 Assembly Manual
Bill
