Description: 6.6L, without dual generators. Express, savana. 6.6l diesel. Without dual alternators. Lgh engine. Allows for the operation of various pulleys, and drive belt accessories, with the use of a single belt Creates a secure point of contact with the pulley, which allows for traction Original equipment parts are designed to work with your GM vehicle safety systems -- aftermarket replacement parts may not meet the same OE safety regulations, depending on the part type

Description: Silverado, sierra. 4.8l, 5.3l, 6.0l, 6.2l. Express, savana. 6.6l. Helps keep drive belt at correct tension to help maintain proper function