The one without the mark wiped through it is the one that is leaking. Out through that hole on top. I am guessing a releif of some sort?My JD 314 has the same or similar sundstrand hydro in it as your Cub. Mine looked just like that. It was an "O" ring leaking where the fan shaft comes out of the housing. Clean everything up good and run it a little and see if that area comes up wet.
Thought i had it fixed but it started leaking again so i ordered one from there. Question i have is why are they half the cost?Same problem on my 1811 rebuilt the whole thing, drove it 10 minutes and it was leaking again. I ordered one from lJ fluid power, the cheapest i could find at 57 bucks. Phone for LJ fluid power- 269-623-4150. Good luck, hope your rebuild works. Part number 9500085