Top port on hydraulic motor?

[Makers Acres]

I bought a TopCat articulated boom mower at auction and have been getting it setup to use on my Skid Steer.
I have a question about the hydraulic motor though. The motor has in and out ports on the top as well as one on the center top of it. What is this used for? Am I supposed to add gear oil to this area? Thanks!

 

[Tones]

It would be for a casedrain connection or to fill the motor with oil prior to first start

 

[Vetech63]

That looks like a Vickers vane motor/pump. Your use wont need anything there.

 

[Makers Acres]

Thank you!

 

[Ctucker]

Case Drain. Don’t use it without connecting it. Will blow the seals in the motor.