My right tank bottom mount was about 1/4" off, not too hard to get right, but the left tank was nearly 3/8. Someone on this thread suggested removing the back screw, and that helped.
I have decided to line the tank with the Caswell product. I sluiced the tank out with lacquer thinner, washed it out with hot soapy water and rinsed it. Got the tanks back on and hooked my air compressor to the bottom petcock. After flowing air through the tank at very low pressure for 24 hours on each side, all bolts will go in without any force. I am hoping that, after I put the Caswell sealer in both tanks that they won't absorb water any more. Then I can try to make the cracks in the outer coat less obvious. Any ideas about spot painting? I not going to get too worked up about an 8 year old motorcycle, even though I love riding it.