Drags are correct. The alloy yoke has 3/4" holes as standard. What you are missing are the stepped tubes which screw into the top of the stanchions. A glance at the parts book will show you these.
36 4G, 37 VH, 54 KH(A), 75 Healey 1000/4, 52/53 ex ISDT KHA (project).
Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser (over a 25 year period).
Now Archivist once more - but not Machine Registrar.