I bought one of these a couple of weeks ago and wish I had known about it forty years ago!
meabh me to !!
Richard I have just checked and surprisingly the outside diameter of the adaptor is 0.25mm less than the original connector.
I use a different grease for the uj's and hence a different grease gun. The connector on that gun has an even larger diameter and I could not get it into the restricted space between the knuckles so I replaced the grease nipples with long reach ones they are M6 and 23mm long, see link. On the subject of greasing the uj's my understanding is they have rubber o ring seals and I am always a little nervous about pumping to much for fear of bursting the seals. When greasing the kingpins I simply pump until the grease starts to ooze out of the joint. When greasing the uj's any recommendations on how to insure you have pumped enough grease without damaging the seals?
https://www.ebay.co.uk/itm/233642984589Regards Tony