Hello , here is a pic of that Clark grader Deas Plant is talking about . Found it at an exhibition in Paris in the early 70's .
It shows the turntable steering and the reach at the left side .
I operated some AW and AB graders , they were powerfull going straight on but I wonder these would be the ideal machines for finishing these modern small roundabouts , since they did not have differentials and starting bouncing when a sharp turn had to be made .
Have a nice day