It's pretty interesting how back in the day there were so many more options and variables on how to run attachments on machines. The scope seemed bigger. Today if you were to buy a loader attachment for your X Series JD, there would be one standard way to run it and that would be it. There probably wouldn't be three or four different options (whether that's in the attachment hook up itself or from outside manufactures) on how you could run the hydraulic system like there were on a machine from the 1970s.
It's always so fascinating to me to learn about all of the different options and manufactures that offered them back then when it came configuring your machine. So many different solutions and each were different. Today, while not completely limited, is a lot more mainstream in most cases.