Pre war tanks have a boss with a protruding 1/4 x 26tpi stud. Post war tanks have an inset 1/4 x 26tpi hole with a groove round the outside of it. So your tank looks like a pre war one where someone has had to modify the mountings for some reason.
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.