I'm adapting a Fisher power angle plow to my 1840. I've never used the aux hydraulics on this. The flat faced couplers at first glance looked like everyone else's AKA universal. I ordered a set on line, got everything put together only to discover they don't fit. The outside diameter of the Case male adapter is almost 1/16th larger then the one I bought. Also the recess on the male half that locks it into the female half is in a different location. Did Case have their own unique version of these couplings???
Early Case used the Parker FF501 & FF502. All of my Takeuchi, Kubota, Yanmar, Caterpillar, and Bobcat use the Parker FE501 & FE502 equivalents. As you've discovered, they don't interchange. You'd be better off switching the machine to the "FE" equivalents, as that's what's on everything now.
You were 100% correct. Mine were FF's. The machine had special couplings with the flare part included that had a lock nut to secure it to the bracket on the machine. I took the full FF number off of it and tried to cross it but was unable to locate a complete assembly in FE. Went to the local hydraulic shop and bought a pair of 1/2 male IPS X flare adapters to fit the IPS FE's to the machine with a large washer to help hold it in place. The adapter tightened just before bottoming out on the washer so there's a tiny bit of looseness but usable with no leaks. Thanks.