I'm in the process of replacing my slush box 518 in my 92 with a stick, while I'm in there I will probably also do the rear main seal. Should this be something that is Cummins only (like the head gasket) or are there other good quality aftermarket seals that are just as good?

 

I have been buying non-cummins ones from rockauto. One was old stock (forget brand), made in USA. The other was a Victor Reinz.

Be sure to get the kit version that come with the seal retainer gasket. No sense in only changing the seal. You're in there anyways.

 

I'm thinking if you have a groove worn in the seal surface it's probably a good idea to install a speedesleeve. Most of the old stuff I've worked on is grooved. Might be why it keeps leaking.

 

Thanks for info guys, it's not leaking at the moment but as long as I'm in there I figured why not put a new one in (probably a mistake, I know if it's not broke don't fix it lol)