Before you use the rebuild kit, check the two screws on the back of the petcock, and see if they have backed out a bit. The only time mine ever dribbled on the floor was due to that problem. If that was the cause, save the new parts for when the petcock finally does begin to drool. If you can find one to check for fit, a non-vacuum petcock from a Banshee looks as though it might work. I'm not terribly fond of the vacuum setup either, and fwiw every XJ engine I've checked the compression/leakdown on has it's weakest cylinder on the one that was attached to the petcock. If you haven't replaced the vacuum hose that goes to your existing petcock, do that the next time you've got the tank off.