Proseal?
The plans don't seem to call for it as I remember. But I do think there is some blanket statement in there about using proseal on ALL screws going into the tank. Paul probably did it right in getting rid of the squishy rubber gasket. I just reinstalled mine after doing a quick check on something and after I tightened it down (with the tank still installed) I looked in there and apparently I tightened one side of the sender more than the other because there is a WHOLE LOT of rubber gasket being squeezed out on one side!!!
ALSO... just to second some advice I got, didn't take, and now am sorry about!! Go get some of the torx screws or even some home depot #8 allen head screws and don't use the phillips head screws you get with the kit!!!!!! One of my screws semi-stripped itself out when putting it in this last time, and will be LOTS of fun to get out without pulling the tank! I might just be taking it back out anyways if that dang squishy gasket ends up leaking as a result of me overtightening it!!! I don't mind redoing it, but I just don't want to come back to the hangar a couple days later and find all my $4.99/gallon fuel just leaked out!!