I repaired the plastic fuel tank on my LS tractor with JBWELD. It has only been about a month, but it is still holding. It had cracked where the idiot design engineers embedded bolts to hold on a limb guard. I would try that prior to putting in a new tank. You may need to put in a backer strip of some type if the hole is large to keep the liquid JB Weld from running thru.