3.0 Cam Tower
 

I noticed when I was cleaning the surfaces of the cam tower that the "plug" at the back (facing the motor from the rear) of the tower where the back end of the cam sits was loose (probably got pushed out by slight cam shaft movement). There looks like there are 3 threaded holes for some kind of keeper etc to go on, but I know I did not remove anything from there. Whats the best way to seal this back up so that it does not either pop out, or leak?

The plug is a "press fit" and there is no keeper for it. I would recommend getting a new plug (Part Number: 930.105.161.00) to replace the old plug. If you smear a thin coat of Curil-T on the edges of the plug before you install it that will provide a little extra insurance against oil leaks when you get the engine running again.