My 58 Ranchero has a drain plug in the bottom of the gas tank. I have had a very small leak since I got the vehicle about two years ago.  I tried teflon tape, but I think the gasohol got to it. This weekend, I tried some gas tank sealer (two part epoxy putty), let it set up for 24 hrs, put in about 5 gals and it is already damp. Any other ideas?