I broke the supercharger tensioner arm this weekend. I muscled it too much trying to get the new belt on. But out of tragedy comes a positive, not wanting to spend $250 on a Dinan tensioner (which is NOT a Dinan made part) I found the following:

The tensioner body is a DAYCO 89201 available over the counter at Advance Auto for around $50
The center crowned idler pulley is a DAYCO 89104 $30
There is one piece of additional hardware which is a bushing for the mounting bolt of the idler, I'm not sure of origin but if you have the old one you could reuse it or measure and order something to match.

The idler mounting hole on the tensioner arm is a 7/16-14 LEFT HAND thread. It is NOT threaded all the way through from the factory (DAYCO). Dinan extends this thread all the way through the arm and replaces the bolt with a Grade 8 fastener that extends through the arm. Hope this helps someone because it took me a couple days to get this info together.