Well, looking at a (rusty) spare atm, it's a 19mm joby, with a 75mm shaft (total), and the shank isn't threaded for atleast............37mm from the head. I think its an M12 thread with a 1.5 pitch, and has a slight point to its end. Thats what came out of mine anyways when I did the bushes, and I reckon its the original thing.