Brad,
You may not hear from Ken for a couple of days, but he always got back to me.
I haven't seen a photo of your situation, but if yours is like I describe below, maybe it will work for you.
I had a similar case with my muffler. Fortunately, the leak on the intake side was a crack in the mudded area around the tube. It seemed to have lifted away from the top about a quarter way around.
What I did, was to find a throw away piece of existing fiberglas I had laying around from a previous project (the thicker the better). I save alot of this just in case. I cut two pieces of glass. I sized them to match the dimensions from center of tube out to the edges of the muffler, & extending larger towards the inside area of the muffler top. Think of it as having a 5" square piece with the hole offset.
I drilled the matching holes thru both pieces, oversized somewhat to allow a min. 1/8" space from the O.D. of the tube to the holes I cut (for glassing purposes). I prepped the tank top & around the tube, and glassed these pieces in. If not sure on the best way to do this, have someone do the glassing. I glassed the two pieces together first before attaching to muffler.
I also bought what is called a bump hose & installed it between the mixing tee and the muffler inlet. It has been holding up for about 10 years now.
If your damage is like mine, this might be the cheapest way to go pal.
CR
I should also add that my problem was caused by vibration thru the exhaust piping that was the culprit. Hence the bump hose.