Black Billet Aluminum Gilmer Belt Drive Pulley Kit for Big Block BBM 361 383 400 413 426 440 Constructed from black billet aluminum, this Gilmer belt drive system is designed for use with Big Block engines including 361, 383, 400, 413, 426W, 426 Hemi, and 440 models.The kit features a cogged 1 1/2 inch wide Gilmer style belt that ensures power transfer and reduces the risk of slippage during.The system includes a water pump pulley, crankshaft pulley, and alternator pulley, all made from black steel with a 1:1 rotation ratio for consistent performance.The pulleys are engineered to work together , promoting efficient power delivery across the engine accessories.The alternator pulley includes outside lips to help maintain proper belt alignment.This kit is built to integrate with existing mechanical water pump setups and is not compatible with electric water pumps.It requires the factory alternator mounting position and is not intended for use on vehicles equipped with air conditioning.All necessary components for installation are included in the package.