Apologies for the slow reply
My upper mounts are as "Snapper" has said, a thick walled fully threaded boss that goes all the way thru the roll bar cross brace & welded top & bottom then the eyelets/hoops for the snap lock of the harness mount clipped onto them.
Just a note.......as it is possible to unclip the harness quite easily from the eyelets I,ve fitted some very small split pins thru a hole that is already there in the snap fitting so that they can,t be easily unclipped.
cheers
andy