Check the axle for perfect smoothness too, where the seal's rubber inner part rubs... I have a 1 1/2 ton that leaks like mad in the same place as yours because there's a gash that looks like some yay-hoo took a cold chisel to it! I have a lot of trouble with that nick, 90-weight pours through there. Even brand-new seals don't quite do it.

Stovebolts are like women; as they mellow with age, it's harder to get 'em to turn over on a cold morning, but once they're warmed up, LOOK OUT!