L4200 bevel gear case and front gear case

[Rainman13]

I know there are tons of posts here about the leaking front oil seals on a lot of Kubota tractors. The last time I replaced the seal on the right front hub was only in March, and it's leaking again already (less than 10 hours of run time ). Reading more about this, many are saying if the seals are leaking, it's because of a problem with the bearings, so I plan to replace those as well when I have it apart to replace the seal. I made a couple observations the last time I had this apart:
1. The bottom of the front gear case had a dent on it, possibly knocking the bottom of it our-of-round. It was tough to reassemble but I was able to get it done.
2. There was a lot of rust on the bevel gear case where the seal sits, that I removed with some sandpaper before I reassembled it.
These two things have me considering replacement of these two gear cases. New ones would be about $1100 and I'm trying to avoid that. I've found some used ones for much less, with one small issue-the part number is from a different generation (lower serial number) of my tractor. I guess this is a long way of framing my question:
The bevel gear case listed for my tractor is part # TA040-12803
The front gear case listed for my tractor is part #TA040-13016
The part numbers on the used parts I located are listed as TA040-12802 (for the bevel case) and TA040-13010 (front gear case). Can anyone tell me if these parts will work on my tractor (L4200 serial number L4200D58693)? I don't see how much different they can possibly be in dimensions, as the bearings are the same regardless of serial number. If I can get quality used parts at a savings of about $800, it would be great.
Sorry for the long-form question, just trying to put the info up front instead of a bunch of back and forth on the thread. Thanks for your help!

 

[North Idaho Wolfman]

Yes the lower serial parts will fit and work.
I think your being a bit foolish on just replacing cases because of a leak.

Does the front axle have a vent?
If so, is that vent clear and working?
Was all the fluid in the front axle changed?
What fluid was put back in it?

 

[Rainman13]

Yes the lower serial parts will fit and work.
I think your being a bit foolish on just replacing cases because of a leak.

Does the front axle have a vent?
If so, is that vent clear and working?
Was all the fluid in the front axle changed?
What fluid was put back in it?

Thanks, I appreciate the feedback. I know it sounds a bit extreme to replace cases to fix a leak, but this is the third time I've replaced them on this side in 600 hours. I'm pulling my hair out. With this leak happening this soon after the last change, I'm starting to wonder if some of the sanding/filing I did to remove the rust or reassemble it made it so it doesn't fit right. The front axle has a vent according to the diagram, but I can't see it from under the tractor. I pulled the plug to relieve any pressure in the case, and it still leaked just sitting in the barn. I changed all the fluid the last time I changed the seal, using 80-90 gear oil. I'm still not sure I will go all-out and replace the cases, but this is beyond frustrating and I'm weighing all the options...

 

[North Idaho Wolfman]

Get into it and take a ton of pictures.
And yes bad bearing are the #2 reason for leaks, #1 is a bad seal.

When you did the first seal was it a 2 piece seal on originally, and the others a one piece seal?

 

[Rainman13]

The bearings are definitely getting changed. I ordered those today. Both of the seals were one-piece seals. I may not be able to get into it right away, but I'll definitely post pictures when I do. I appreciate all of your help.

 

[Rainman13]

The bearings are definitely getting changed. I ordered those today. Both of the seals were one-piece seals. I may not be able to get into it right away, but I'll definitely post pictures when I do. I appreciate all of your help.

I took it all apart and the bottom of the front gear case is definitely out of round. I had a heck of a time getting the bottom bearing to drop out. I found a used one and measured it with calipers. It measures 2.80 +/- .04 all the way around. The old one varies from 2.814 to 2.781. I can see a dent on the outside where I must have hit a stump or rock. There's some rough spots in the bottom bearing when I spun it, and it was stuck together with the lower bevel gear.
I found a used bevel gear case too, but I think I'm going to send it back. The one on the tractor looks in good shape and measures round within .002. There's a little bit of rust where the seal fits, but it's above the seal so I don't think the leak is coming from there. There was also a small drip between this case and the axle case, but when that leaked on the other side I replaced the O-ring and was good to go.
So long story short, replacing O-ring (part #04811-51050), Keeping the old bevel case, new oil seal, replacing the front gear case and all the bearings that are inside of it. I'll keep you posted...