Leaky rear diff jd 790

[Seanshandyhauling]

Leaking from rear diff jd 790 see pic arrow points to hole been leaking for nearly a year when i load in trailer i notice most. Dump trailer steep incline. The stick reads half full its came down from the top of full over about 8 months since last fluid change. I assume its overflow leakage but not sure. Pretty sure about where its coming from. Is this normal? Is there needed repair? About to change fluid and give good washing under the tractor but just wondered. Should i fill less or what load and unload the tractor pretty often from my trailer.