How to replace supercharger idler on 1998 Buick Park Avenue

The supercharger belt is missing and the lower idler is missing.

Asked by for the 1998 Buick Park Avenue
You can buy these parts at the dealer or at an auto parts store. You don't say whether these parts were on the car when you got it. I'm suspicious that the supercharger is faulty and someone removed the parts.
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