The seal goes on dry and for this reason is because the seals have a thin coat of theflon and when the crank spins the seal to crank has been bonded together..If you apply them wet than the theflon won't make the bond with the crank.I put mine in wet, on my 4bt and 6bt and they are fine. I know cummins says to put them in dry, but I just couldn't do it!
poolmike you are doing a rear seal correct? I just noticed that BobS and CrewCab59 have been talking about the front seal. I don't remember offhand if there's much difference in the install between the 2 or not just thought I'd mention that he's doing a rear and not a front.
Your rear seal should come with a seal install ring that sets the depth of the seal into the rear seal housing.The seal is the same on the 3.9 and 5.9 .Is there any special way to install the seal, or just gently tap it in moving around perimeter? Also, does it use the same seal as the 6BT (for ease of locating one at parts store, all years same?)?
I figure I may as well throw in a new rear main seal before bolting drivetrain together.