FELT DONUT BEHIND THE STEEL CRANK BALANCER

cudamark said
I've seen many on later engines too........ones that had been apart before.....not on virgin engines. If you look in the '68 factory parts manual, that felt is no longer shown, and a new part number seal is used.

.....and I admit, I cannot be SURE if those later engines I saw them on were original, however, I am almost certain my 77 was.