I just measured the petcock thread diameter and used one of those step drills to make a hole in the bottom of the bottle, liberally smeared JB Weld to the threads and around the hole inside and out, then screwed the petcock firmly into the tank. I have been checking it regularly and so far no sign of a leak.What size hole did you drill for the petcock. I’ve got a leak in the stock gas tank and I’d rather not buy another dud