Couple of things to consider..where on the seem..bottom,middle,top.
How big is the leak.
Does the metal of the tank seem solid..good shape w/little rust.
What the replacement cost of a tank.
If the metal in good shape and the leak near the top I would consider a steady hand trying to patch the leak..but if the leak near the bottom and the metal not all that good shape I would seek another tank..ain't nothing worse than leaking gas tank in the back 40 on a hot summer day,or the dead of winter trying to patch the hole again or replace the tank. /w3tcompact/icons/frown.gif