Looking this tread over I don't think you guys really understand how a rear end gets it's lubrication. If you understand what this about, all the other peices will fall in place.
As the gears and parts of a rear end rotates at high speed, in and out of grease, a
oil mist is created inside the housing. This mist is what lubracates almost ALL the parts in your rear end, (not the ring and pinion)and believe me that mist will go everywhere inside the housing. Axle housing seals are in there to provide a place for the mist to drop out (not all of it though) into a
oil liquid. Thats why some axles have a sprials cut into the axles, to help spin pump that
oil back to the center section, and other "makes" pump oil towards the bearing. This depends on the design and explains why some rear ends should not be narrowed. Now some wheel bearings are open to the oil mist, some are totally sealed w/ their own grease, some have a external seal outside the bearing. WHATEVER. In the case of all the 9 inch Fords I've delt with, the bearing is open towards the rear pot and sealed to the outside, and relys on the mist for lube of the bearing. There may be however a sealed bearing out there on 9 inch Fords that I don't know of. No matter,,,,,
All is well till the rear end cools off. Then condensate gets into the oil and on a cold startup that oil mist/water mix will congeal into sledge when it cools, that is, if the rear end never gets hot enough to boil off the water out of the oil and vent it off via the housing vent. Thats why there is sledge coating inside most used rear ends too. Those bunny hops we all make builds up sludge in your rear end. (sounds perverted now doesn't it?)
Those axle seals help prevent sledge buildup in the wheel bearings and subsequent seal rot. If you don't put axle seals back in a fast cornering car such as a Cobra, live liquid hot grease
can and does get to the bearing. This does no harm to it at all. Fact is, it may even knock off some off the sledge buildup in the bearing. When a 9 inch Ford leaks oil at the housing ends, most times it's because of a rough housing end, and my silicone trick above will almost allways fix it. I've also fixed or slowed down 3rd member gasket leaks on bolts above the oil level in the past by simply clearing the housing vent. Works wonders! Remember we are talking about a pressurized oil mist here.
If you think about what the oil does in a rear end, the things you can and cannot do fits a bit better in place.
BTW- In cars such as a Cobra DO NOT run c-clip axles. Way too dangerous. And that's not a thing I will even debate about.
cobrashock