I guess it depends on the year. They used rope to a certain point, if I am not mistaken and then switched over to the two piece modern seal. Maybe @slantsixdan can enlighten us on that. I think I am going to try one of those one piece seals on it though. They are available for the big block, which is the same seal as the slant 6, so I may try that. I'm not 100% sure my seal is even leaking, but if I pull it back out, it's gettin one. lol