Hello !
The three plugs which are in the block "valley" of my 5.0L block are not identical.
The aft plug nearest the bellhousing has an internal thread, the center and the forward plug only have 6mm hex insets.
Can somebody please explain the reason for the differences in these 3 plugs?
Thank you. Dan

 

No experience with that year but I think the threaded one is for a single knock sensor. In the S4 the fore and aft are threaded for knock sensors. I'm sure there are better informed people who will chime in.

 

What you have there is a S3 block. The threaded bolt is where the throttle body buffer screws into.