Runs good, but has a leak....

i had the same problem a couple months ago witha customers car (71 340 cuda) installed it with the new gaskets and bolt was ok for a couple of days, then it started to leak (only when running obviously, but when it did it did!) i went underneath and it seemed to still be loose.(i know i tightened the crap out of it!) i reinstalled it with a skim coat of sealer and to this day it doesnt leak. i had to run the adapter on this car due to installing 68-70 340 manifolds (this is the reason 340 cars use the adapter) if your running headers though you should be able to remove it all together....