Awesome responses. Thanks Mike, Uncle Brad, and Bartamos.
I think I remember scraping some type of tar paper off the floor when I was cleaning up my cab. There was none stuck to the gas tank. I'm assuming the tar pads lift the bottom of the tank enough that the seam doesn't rub in the long channel where that sits. Or maybe it's the humps where the straps bolt down.
I should be able to get this plumbed in today. Truly appreciate the advice.
Jim