This is a new replacement large gear for the 1969-70 Ram Air V and the 1973-74 455SD which used a smaller cam gear and larger distributor gear to reduce wear. With the factory 80 Melling oil pump. It is made from the same material that our standard Pontiac polymer composite gears are crafted from. It can be run on both steel billet roller cams and cast iron flat tappet cams. Polymer composite gears it will outlast.491 bore but can be reamed to. If you are using a standard cam gear and running an 80 lb oil pump (Melling 54DF) we recommend our standard polymer composite gears available in both. They fit all Pontiac V-8, just match the bore with your distributor shaft size. They can be run on both steel billet roller cams and cast iron flat tappet cams. This item is in the category "eBay Motors\Parts & Accessories\Car & Truck Parts & Accessories\Engines & Engine Parts\Crankshafts". The seller is "wadecongdon" and is located in this country: US. This item can be shipped worldwide.