Bolts to the head and top water pump bolt holes, for use with factory Chevrolet steel pulleys and a reverse rotation LONG WATER PUMP. The alternator bracket will fit all '69 and newer heads. The A/C compressor bracket fits all GM aluminum heads by drilling and tapping one hole for the upper mounting point.
Part #305 will clear up to 3-3/4" tall valve covers when used on '86 and earlier heads.
Part # 306 will clear up to 3" tall center bolt valve covers when used on '87 and later heads, including the VORTEC heads.
Part #'s 307 & 308 are designed for vehicles with low hood clearance and wide engine compartments.