finally Stopped oil leak

Good deal.
What about this seal?
Is it the Viton?
A reputable shop replaced the rear main on my BB 383 in the car, with the two piece Viton, twice, and it still leaks! Even tried the billet cap most recently.
The crank surface looked solid, and seal was installed correctly.
This is the 2nd seal after a fresh rebuild (stock Felpro seal from a different engine builder) leaked.
Frustrating.
Joe
Was it line honed?