Okay now, got back from the in-law thing, took a nap, and got at it. Got the tank out with not much problem, just not simple to do.
When I get it back in, it will be done so it is easy to replace if necessary again. Let's hope not!
Drained the little that was still in it in the swamp out back, filled with water, sloshed it around real good and drained in the swamp. I'll let it dry before starting work on it. Got plenty of time to do it, but want to get it done. You can see it's "L" shaped, about 43" long on the front side, 32" or 33" on the back side, indents about 8", then about 9-1/2" to the right side, and about 21" wide on the left side. About 6-1/2" deep at the right side and about 8-1/2" deep at the left side.
I'd love to get one of those Pipe Piranha things Eddie mentioned, but it's about 10X out of my price range! I'll have to look at these forstner bits, as I'm not familiar with them. I have a shop full of tools of every description, but no doubt will need something I don't have. I have a few ideas about how to do what I need to do, but think Eddie's idea about a rubber coupler is right on.
I'll keep ya all posted as I get at it. Rebuilding a Honda ATV motor right now too, so just busy!
Thanks for all the help folks.