I have had my Troy-Bilt Horse for 6 years or so. Ever since I've had it, it has leaked gear oil from around the axle shafts. Last fall, it was really bad, to the point where I had to put a pan under it to keep from making a huge puddle on the shed floor. Well, I finally ordered and replaced those seals, and from what I saw, they were the originals from 1974. Once I drove the roll pins out that held the wheels on the shaft, they were amazingly easy to replace. I used the Stens seals.... not the cheapest, and not the most expensive seals, either. Less than $10 fix. We'll see how they hold up.
OBTW...... I LOVE that old Horse!!! Probably my next-most-favorite piece of equipment, just behing my IH Cub 123 that has a #1 tiller behind it. The only tiller I would like better might be a BCS, if I had one. If money were no object, I'd have one of those, too!