Just bought a new serpentine tensioner from my local GM dealer. It came as a 2 bolt mount instead of 3, dealer stated it was superceded new part.
Maybe on a stock motor it might have been OK....maybe. However with the Procharger D1 it lasted 2 days. It slowly bent forward till the belt walked and threw it. Bent the lip on the tensioner pulley and sliced the new Gatorback belt. Dealer looked around and found the org style and is going to replace it but just a "heads up" for everyone with a Procharger.

 

i was able to get a 3 bolt one from the local parts store, I'm 90% sure it was a gates part.

You might want to try that angle.