Is your Cummins leaking oil at the rear of the engine? Chances are its your rear main seal that needs replacing. We offer this seal in two different options. The first, called "Rear Main Seal" is an exact replacement to the seal thats currently in your truck and a great option if your crankshaft is not worn. The second option, "Rear Main Seal with Repair Sleeve" features the same great sealing properties as the standard seal, but includes a "speedy" or "wear" sleeve intended for trucks that have a worn crankshaft surface, to ensure a complete seal.