That's the lip seal that was designed to replace the rope seal. On some engines they're interchangeable. What's the condition and oil clearance of the rear main bearing? If the crankshaft can bounce up and down on a loose main, no seal is likely to hold for long. The lip seal also works best on a very smooth seal surface- - - -if there's a groove worn in the crankshaft or any roughness, you're probably better off using the rope.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!