Just a word of advice: Go to the rear of the tractor and look at the position of the oil level plug and note how far it is off the floor. In the opening where you are at there is a couple of seals, however there is only one that is below the oil level. It is inside the driven gear and seals between the gear and long PTO shaft going to the back of the tractor.
A lot of guys have overlooked this seal and complained that it still leaks. I have looked at too many tractors, answer: DUH didn't see that seal!