The arrow in Brian's pic is pointing to the correct nut. Kinda tight to get at from the top, but you can, I have usually gotten them from the bottom...but I admit I am usually checking them during a t-belt service.
Removing the charge air tube near the PS reservoir (on G/J models anyways) will help.
Matthew, all the failed controllers were ALH cars, manual or automatic, and they were all 2000 models, if that narrows it down. The other folks that had the same problem may have had different model year cars, not sure.
Blue Hen, your PD is arranged a little different, but that big aluminum barrel thing in your pic is the BACK of the compressor.