have heard that the 258/ amc rear main seal, one piece is a better way to go. whats needed to do this as am replacing the trans next week and would like to do this? thank you...jim

 

I am not sure about the small block, in the big blocks you use a 460 ford seal it is a one piece seal. check it out a your local NAPA

 

That is NOT a one piece seal that installs from the rear. It is a 2 piece neoprene (sp) seal that replaces the rope seal. It installs by removing the #5 main cap, so having the trans off has no bearing on it. The 258 AMC seal works, but you have to trim off the "ears", it is readily available at parts stores. The old 292 Ford seal also works (Fel-Pro # BS 6141) but you may have to order it.

citcapp, you are correct that the 460 seal works for the BBO, but the SBO has 2.5" mains, so it is a no-go.

 

To expand on what captjim wrote, it is not physically possible to use a one piece seal on an Olds crank, as the flywheel mounting flange is larger in diameter than the seal journal. The seals mentioned above are TWO PIECE neoprene lip seals, which are still much better that the original rope seal.

 

thank you guy's.