Take the tank off and of course, drain all the fuel. When I installed mine, I put three 'shop towels' (old, very soft, worn out bath towels) on the bench and because I had drained darn near every drop of fuel and left it sit with the cap off for awhile, I was able to work on the tank with it upside down. When I bought my Pingel, it came with a mounting adaptor that bolted to the tank and then the petcock screwed into the adaptor. I assume the new ones do too? If it comes with a lightweight paper gasket and some blue sealer that goes between the tank and the adaptor, get some proper gasket material, some Seal-All, and do it right. I used what came with the Pingel and it blew out with about 2 lbs. of pressure (followed the instructions to the letter). I ended up using red RTV and some gasket paper and it hasn't leaked (probably 2.5 years) since. I also used teflon tape on the threads.
Let us know how your install goes?
