I finally got some time to work on this so we split it at the bell housing/transmission joint(2nd joint from the front). There is a lot of plumbing and other things to remove. Upon inspection before cleaning up anything it looked like it could have been leaking on the right hand side of the hydrostat pump at the gasket. I ordered up the New Holland pump seal kit that cost $383 all by its self plus the 4wd sealed bearing that stays with the front half and the 3 seals that are in the case just behind the transmission. Thought I'd change as many parts in there as I could since it was quite a pain in the *** to get apart. Also ordered a new throw out bearing as mine was starting to sound dry.
When the parts arrived we changed the 3 seals in the rear gearbox. Just drilled a small hole, threaded a small sheet metal screw just enough to grab. Then hooked up a small slide hammer to the screw and easily popped out the seal. Replaced the 4wd bearing and throw out bearing.
After cleaning up the outside of the transmission we unbolted the 4 bolts of the drive pump. They were all very tight. Possibly too tight. Carefully opened up the unit and right away could see that the gasket had walked inward on each side. Right then it was obvious that this was the cause of the oil leaking. I tried to see if I could make the gasket fit back in a straight line on the sealing surfaces and it would have nothing to do with that. It was now formed with a curve on the sides. While I was clean off the surfaces you could faintly see the outline of its original position with nice straight sides. The service manual says to stick the new gasket on one of the surfaces with Vaseline to hold it. I thought this method may have contributed to it moving after assembly so I decided to use spray on copper coat gasket prep instead.
I took the back motor side apart to see if its gasket had moved and it had not. Could have left that one alone. There is a small spring and poppet that you have to get back in just right. Not too bad though. I changed the back PTO and Drive output shaft seals. Then decided not change any more on the tranny because none had shown any signs of leaking.
Put it all back together, Filled the oil, Fired it up, And all is good now. I went and did a couple hours of hard brush mowing on one of the hottest days of the year and haven't seen a single drop of oil on its belly. I couldn't be happier. Worth spending 4.5 days working on it.
One thing that I would have done differently would be to take off the hazard light brackets before removing the fenders. They end up being right in the way.
One thing I noticed while cleaning up in the back half(dry case) case where the transmission mounts is my mid mount mower mount covers the weep hole and cotter key in the case. Basically blocks it completely. If it didn't and you had a leak you could most likely tell if which end it was on because there is a high spot between it and the one in front.
Hope this info is helpful to someone else.
I think I could have got buy by only changing the front pump gasket. It is the $115 one not the $20 one if purchased separately.
