Buy 2005 Chevrolet Trailblazer EXT LS Sport Utility 4.2L Vortec 6 cylinder A/T RWD Accessory Drive Belt - OEM Chevrolet Part # 12573024 (24576885)

Tensioner. Belt. Accessory Drive Assembly. Serpentine.
Assembled device that applies load to the Drive Belt.

Accessory Drive Belt Tensioner Assembly

3.5 & 3.7 LITER. 3.7 LITER. 4.2 LITER. All Models; 4.2L. Canyon, Colorado; 2.9L, 3.7L. W/AC, 2.9 & 3.7 LITER. W/O AC, 2.8 & 3.5 LITER.
Drive Belt Tensioner - Repair or Replace
A squeaking or squealing noise from your engine bay is usually due to a loose drive belt. Consider replacing the drive belt tensioner on your 2005 Chevrolet Trailblazer EXT.