'97 F 150 4.6 L- just giving a heads-up for all of you with this **** poor engineering problem by uncle henry. i have seen many of you with the same problem and it happened to me... leaking exhaust manifolds at the y pipe due to failure of the studs, and failure of the manifold to head studs. mine started as the pass. side manifold to y-pipe leak. on inspection i found both studs RUSTED in half, and one rusted in half on the drivers side, the other hanging by a thread! i dropped the y-pipe out, drilled out studs and replaced with bolts. all was well for about 1 month, then pass. side manifold to head studs failed on the rear most cylinder. needless to say i was thoroughly PISSED!!! well i didnt have the time or patience to tackle this, and when i talked to dealer found i didnt have the cash to have them do it either!!! well i let it go for about 8 months...DO NOT DO THIS!!! fix it as soon as possible! when i finally got to the 2 studs on the leaking cylinder were badly corroded, and the only 2 that didnt come out easily. the top one was broken off about 1/8" below the head surface, and the lower one was intact but wouldnt budge. i used cobalt bit, right angle drill, and screw extractor to get top one out fairly easily. the top one i cut off w/ die grinder and did the same procedure, plus slighty grinding away the corroded aluminum around the stud to relieve it. i hope this helps anyone that attempts to tackle this. i plan to buy after market iron manifold, and will let the drivers side go for now as it is not leaking. would like to put headers on but not in the budget at the moment...