That's what I had to do.

We have 2 belts and 2 tensioners on our GTP's. The one with the heater ports is towards the firewall for the "normal" serpentine belt. The one towards the car's nose is for the supercharger drive belt.

Every place I went to did not have the S/C tensioner. I resorted to the dealer. I think you could get it from www.rockauto.com, but I was under time constraints.

$80.52 later, I ended up with part number: 12564506.