We have gone to great lengths to custom make these Big Block Mopar O-ring kits in premium VITON material. Viton is made by Dupont, and has much greater resistance to high temperatures than standard rubber. It also doesn't have a tendency to dry out and shrink over time while sitting, which makes it a great choice for cars which will sit for months or weeks in between being driven, virtually elimating leaks and cracking, etc. Overall, Viton is considered a top of the line material to use for any area inside an engine which is sealed by a rubber material. There is no other way to get VITON into your oil pump besides ordering these kits, and replacing the O-rings yourself, which is super easy to do by just removing the two bolts which hold the cover onto the body of the pump. These O-ring kits are very convienient for when oil pumps are being rebuilt and/or disassembled. These kits include all three O-rings used in a big block Chrysler oil pump. The small thin one which seals the neck of the pump to the engine block (shown in the picture as #1), the small thick one which seals the oil passage from the pump body to the cover (shown in the picture as #2), and the large one which seals the rotor gears to the cover (shown in the picture as #3). Avoid oil leaks and blowouts with this easy to change and economically priced kit. These fit Melling and other similar style CAST IRON pumps, including standard, high pressure and high volume.