Hard to find these things----are not reproduced.
Even the sending units are obsolete now.
But---I did have a major brain fart.
I just took it to the body shop (I spend a lot of time there), after I realized that Hector fixes bumpers all the time.
He had me clean the tank off, get my dremel, and clean out the crack and put a "V" in it.
He then warmed it up and "welded" it closed again.
The crack is (was) at the top on a factory seam, so when I get around to putting it in my truck (hoping existing brackets will work as this tank is larger), I will put some neoprene or some kind of rubber every place the tank comes into contact with the frame.
I probably would have never even noticed the tank was cracked, had I not tipped it on it's side and then saw it start seeping.
Next----on the hunt for a good sending unit.