RickB, your analysis is spot on. I figured it out just after I did the post. Once I determined there was no vent and thought about it I concluded that it was not vented by design. Venting could allow dirt, water, etc. to enter the gear housings given the conditions a tractor is exposed to. A couple of advantages of having positive pressure inside the gear housings are; 1, making it more difficult for foreign matter to enter, 2, when the seals start to fail it will push oil out. So it will be noticed and can be corrected. The seals were original and 25 yrs. old, the looked fairly simple like packing. Whereas the new ones have a dust lip and a primary lip, they should be more effective. Before I opened the gear cases up I drained and looked at the oil, no metal, no burnt smell, no water, and the level was correct. I also jacked up the front end and checked the axle for vertical and axial movement, ok, turned it over by hand and no noise or clunking. So it was quite clear it was just the seals that were the problem. Had it back together last week and ran it quite a bit over the weekend, everything is fine now. Thanks for your input.
