That is an interesting piece.
The "typical" diverter valve is the block Behind the fitting with the thumb wheel.
The two banjo bolts above the hydraulic lines are threaded into this stock diverter valve. That small steel lever that sits against the stop is the "diverter" control that send fluid out and returns. it turns 90 degrees to block flow to to any "Power beyond" additional circuits.
I'm trying to think just what that screw knob valve might do. Speed control perhaps.
Having that "extra" bit and not knowing just what it was for would drive me to remove it and observe the nature of the mechanism.
Fortunately for me, my B7200 hst is not fitted with a loader, and does not have that added fitting. Only the one behind. ;-)
But if you are so driven, let us know what it does ;-)