Have you tried changing valve cover gaskets? When they go bad they can leak a lot of oil. Since you have a diesel, you can plug every hole in the engine crankcase and she still won't chug. You don't have a PCV valve pulling vacuum on crankcase since the intake of your diesel has no vacuum. Vacuum is created 100% by vacuum pump which dumps into the crankcase so it would do no good to attach a PCV to that. By plugging all the holes all you will accomplish is a lot of blown seals and gaskets.
'96 Dodge 3500,KDP killed, boost-pyro-trans temp, not stock anymore
'01 Dodge 2500 4X4, EC, LB, 6 speed, FP-pyro-boost,
'97 Chevrolet Suburban, K1500, 4.10 gears