Large O ring on dizzy? Rubber or other

Great info guys. So right now I have a big thick (hardened) Oring which presses up against the hold down strap. Then on the shaft there is a groove, and in that groove sits a very thin oring, much thinner than the groove itself. I have never seen colored O rings at the Auto store, just the black ones. I have never seen any oil on the Large O ring, nor have I ever seen any oil leak from the distrib.
There are many different colored o-rings, but they aren't part of a std. "kit". Some are different materials for different temp. & fluid compatibility, others are coated to help
ease of assembly. Look at some stock applications like fuel line quick connect fittings, they often have a mix of black,brown, or yellow o-rings. The yellow ones are almost
always the "back-up" ring, i.e. the first one You see inside, but the second one fuel would see trying to leak, that yellow is a coating that will come off if You try. A/C ones
can be green, blue, orange(also used in water fittings, and vapor/intake fittings), primarily green....and it is a coating to ease slipping the connections together.