Red PT owners, what is this for?

[Highridge]

On the lift arms of my 1430, there are 4 quick connects - 2 PTO and 2 Aux. PTO. There's also a 5th one on the right that is just there. It's not on the green Pt's. I thought it might be for something like the Knuckle Boom Mower, but there's nothing to control it.
Let's see if I can post this pic right.

 

[Bob999]

The connection is for a case drain that many hydraulic motors use. (The case drain allow a return path for hydraulic fluid that leaks around the motor drive.)

 

[Highridge]

Have you ever had to use it? How would you use it? I wonder why the smaller Pt's don't have it.

 

[Bob999]

The mower for my PT 1845 has a case drain hose and I use it every time I use the mower.