"Best" is the choice of almost everyone.No machining required.Even comes with instructions.If you go to Ted's business website there is more info on this rear main seal.(Eatonbalancing.com).Click on articles.

  

John Mummert, Red's Headers, anyone who carries Best Gaskets...

BOB

I originally built my the 312 with the rope seal. Since the motor is still out I wanted to convert to the new neoprene seal. Any recomendations on who supplies the best one. I think I saw red and black ones. I just assume no machining is required.

Thanks,

Richard