There are safe ways to alleviate leaks in old gas tanks.
My favorite is to buy a new one.
I just think ahead about how hard I would be on myself if my truck caught on fire one day because I was too "thrifty" to spend $200 to $350 for a new one.
Carl
That's what I did,the exterior of my original tank was perfect,the inside was another matter.
Dropped the cash on a new tank and it leaked at the filler neck.

Rather than go down the fibreglass route I mentioned previously I found "Petro Patch putty" a two part epoxy,it's worked a treat.