After the 5-20 installation of the tank I found one of the top 5 screws was stripped. Didn't have time to fix it correctly so I thought I'll just smear all the gasket surfaces with extra sealant and it will hold, It didn't.
For the fix made all of the blind holes through and added studs. Used 1.5" 8-32 screws and coated the head and threads with red loctite for my "studs". I don't expect any more leaks.
At least now I can do maintenance on the sending unit without dropping the tank.
Trace the air leak down to the flex line I'd used to extend the fuel pickup. I'd used SAE 30R7 fuel line (for external use only). I had let the fuel level drop and it exposed the fuel line to the air inside the tank and it started sucking air. The correct fuel line type to use for submersible usage is SAE 30R10. There very proud of it, $25.00 a foot.
So now I've run two tanks through and let the fuel level drop down to E twice, no problems.