Ok in the crankshaft seal kit, it comes with a couple things. The instructions are extremely vague about the parts. In this pic: http://media.photobucket.com/image/cummins%20crank%20seal/FiveNdime/Forum%2520Stuff/CumminsCranshaftseal.jpg It shows the seal, install sleeve and a piece of metal ring. I dunno what the other black rubber ring is, as I have not had one of them in my kits I bought. Although, I have gotten the metal rings in mine. It does not say what it is for and when I first removed the dampener, there was never one between the crank seal and dampener. Anyone have any idea what it is for? If its important to have, I need to know soon, as I have a new crank seal in!

Weird. I have no idea what the black rubber thing is for. Like you all I have seen is the seal, plastic piece and the metal ring.

It is just a dust seal or slinger for the crank seal itself, just a little extra protection. it slips onto the crank between the seal and the dampner, it will spin with the crank, the open side or grooved side goes toward the seal.