First, a question. I used a shopvac on the fuel vent and sucked up quite a bit of diesel fuel(from a bone dry tank). Should there be a low spot in the vent hose that can trap fuel? Finished capping my two six-inch cleanout ports in the diesel tank yesterday. When I bailed and soaked up the last pint or two of diesel fuel I did find some goop. It wasn't real bad but I am glad I got it out of there. The pickup tube comes down that inside seam to within 1/2" of the forward end of the tank. It would take at least two gallons of fuel before the gauge float would move to the 'E' mark. If you were to cut a cleanout you should only need the one near the gauge, on the forward side of the big baffle. Everything will run down to that forward/inside corner at the pickup tube. Center a six-inch hole at the location noted in my previous post. I made an eight-inch plate out of 1/8" aluminum and drilled twelve 5/16" holes. Used that as a pattern for 1/8" gaskets. Also used to lay out the 1/4" holes which I drilled and tapped. Hardest part is getting the tank spotless of drillings, filings, and thread cuttings. Then non-hardening Permatex with the new gaskets. Well at least I now know the tank is not a problem. And probably never was.