Both manifolds. Clearly they did not want to do it. They were going to take the engine out and replace both manifolds. They said that even though the driver's side isn't bad yet, it will be soon. The passenger side has both studs broken in the head on the front cylinder and they said that removing the engine allows them to drill out and remove the broken studs. I am sure that they are right, and it makes sense to do the driver's side once you have the engine out but they really just did not want to do it. I thought I had a pretty good relationship with the service guy, I have been taking my Explorers to him since I bought my 2002 Explorer there new.
By the way, Explorer_PL -thanks so much for your detailed description and pictures! It was very helpful to see your picture of the motor mounts. I was able to jack up that side of the engine and pull the old manifold out the top. I still have to get the broken studs out, and I am trying to figure out a way to get a drill in there. My DeWalt Right angle drill is too big. I bought the Lisle 68500 Manifold Drill Template for Ford 2V & 3V for drilling out the studs, but I fear that it takes up too much room and I won't be able to use it on the bottom stud.
Did you remove the A/C condenser to make enough room to get at the bottom broken stud?
Thanks again!