Used GM automatic accessory belt tensioner.   This is for the alternator/water pump/power steering pump/balancer belt only, and mounts on the water pump.   Fits the following:

98-02 V8 LS1 Camaro Z28, SS
98-02 V8 LS1 Firebird/Trans Am
04-06 LS1/LS2 GTO

NOTE : This does not fit Corvette nor Trucks!