Hi Team,
from memory the No 41 Hyd. Controls were mostly used for Tool Bar set ups where the Blade/Tool Bar arms were swung from facing the front for blade use or to the rear for tool bar use without disconnecting any hydraulic lines.Scans below are what I have saved from here courtesy of others and may help explain.

The Diverter or Crossover Valve as Cat call it, would be fitted to the end of the lines on the right fender coming back from the front tank unit and so then diverted for desired implement use.

Cats Crossover Valve was also used as a Diverter Valve at the same time as seen in the scans below.

The 41 HPCU could also be supplied 2 or even 3 control valves.

Hope this helps.
Cheers,
Eddie B.

A cross over valve was not used on #41 systems. It was used on #44 systems only.
The #41 could have 1, 2 or 3 valve circuits. Might try looking for one with additional valves.
I have seen some neat installations of "Prince" rear mounted PTO pumps but you do lose the constant pressure supply when disengaging main engine clutch.
Here's one on a D2 but you get the idea....
 

        I will try to post some photos of the valve and piping for my 44 on a D4 6U. They are just like Eddie posted from the manuals.  Not sure if this worked, and yes I need new hoses.

OK, the photos show how badly I need to install new hoses, so a question ??? Where would I buy the correct hose for these old style fittings? Grant.