Grr camera battery flat... but I found quite a good photo here:
https://www.ebay.co.uk/itm/Massey-Fergu ... SwlrFaw4XE The back-end casting is basically the same as the Dexta, apart from an extra 'ear' at each side, and there is a long pin goes through them + the bottom of the top-link rocker - visible in the photo, although in this case someone has fitted a long bolt and nut. The 'correct' pin has a hinge in the middle, to make it easier to fit in.
When using a Fergie with a loader, or tipping a trailer, you need to stop the link arms coming right up, otherwise hydraulic flow is cut off; so you need to either use the pickup hitch with T-bar, which fits on to the long pin, or, a 9-hole drawbar with stays, also on to the pin. If these were fitted on to the normal top-link mounting, then lifting the hydraulic lever would compress the top-link plunger, and again, cut off oil flow. So the more modern Dexta, with its hydraulic external-services plunger, doesn't really need the extra attachment to the backend.
Things like this were quite common too on Fergies, I think, in the days before the modern swinging drawbar:
https://www.ebay.co.uk/itm/Ferguson-Dra ... SwhEla7s3h (I don't know why they mention the Dexta, because it would obviously
not fit it)