Check the listing for details. Pontiac Composite Distributor gear for Solid & Hydraulic Roller Cams w/.500 Bore. Condition: New. Listed at 159.99 USD. Solid roller and hydraulic roller cams are made from steel cores rather than cast iron for hydraulic flat tappet cams. The traditional fix for this was to run a sacrificial bronze gear which failed in short order. BOP Engineering's ultimate distributor/oil pump drive gear for the traditional Pontiac V-8 is crafted from a proprietary carbon composite, this gear replaces worn bronze distributor gears and are a must for any roller cam or cast iron cam, especially with higher pressure oil pumps. Do Not confuse these with melonized gears. Melonizing is a surface treatment that will wear off quickly. There is no comparison. These gears have 20 years of proven street and track performance and durability may be the last one you ever buy! Never worry about metal shavings in your oil again. PDG37 and PDG38 gears fits all standard Pontiac V-8 cam gears. Shaft sizes include .491-inch for stock applications and .500-inch for MSD and other aftermarket distributors. BOP Engineering www.bopengineering.com has been providing high quality parts for Buick, Oldsmobile, and Pontiacs for 25 years. Avoid sales tax here https://www.bopengineering.com/A_Pontiac_Engine_Alt_Ignition_Valvetrain.shtml