Back in October I noticed some coolant leaking at the base where the intake manifold meets the head. Took it all apart and it was the intake manifold gasket that gave out underneath the t-stat housing area. My 99GT has 110k miles on it and I knew the history of these crappy manifolds and figured I was on borrowed time, so I replaced it with the new FRPP manifold, pretty easy job, and no vacuum leaks (thank God!!!)