I have only seen O rings on rebuilt distributors.
These same distributors are usually missing the wear disc, spring and grease cup.
Good tip there from Pre ‘68 Dave
The reman distributor I got from napa was missing the spring and disc in the grease cup
They also added that o ring that gave me fits when trying to drop it in (came on this site and was advised to get rid of oring)
If you click on Pre ‘68 Dave blog in his signature he has a write up on adding a disc and spring
...his link...One good thing about that distributor from is it came with a vac advance. I don't think its included anymore. If you send your back for a core chanrge remember to remove the vac advance.
