Stop in for a cup of coffee

halifaxhops said
I have no idea how it does the shaft is smooth. Crankcase pressure?

No idea either. The race units had the grove cut in the shaft. Done pretty crudely on the one I have.
The standard MP units for small blocks have the wider nylon. Were they reducing oil getting up there? More support for somehting ? I dont know.

Mallory built ones used a bronze collar IIRC.