I can say with certainty that my engine code is S52US

On the topic of I-Bus, I rebuilt my interface again on the breadboard, but unfortunatly I still am not able to read anything off of it. Oddly enough my I-Bus seems to pull to a constant +10.5V, though my CD Changer functions fine.

In the back of the manual for my headunit, it does indeed refer an I-Bus pin, so i can verify that I've got it. I suppose I'll try rebuilting my connector once more Thanks for all your help!