Mine is dry with Superformance main seal and Mancini billet retainer. Greg has explained many times on here about how to install a rear main without leaking. I install mine on a slight offset and make sure the retainer is centered in the saddle.
I opened up the holes slightly so when I slid it into place it was centered around the journal. Just make sure your pan is seated on the rear pan rail and not raised up on the studs.
I once thought my rear main was leaking but it was the pan and windage tray raised off the rear pan rail by the ARP studs.
Gus