All early Sovereigns and Olympus with S8R had the 075 mounted to the baffle with the split ring collar. Not until about late 72' (I think) did the 4 hole square mounting flange get added to the 075/2402/2405. Sometime in mid-late 73' JBL stopped using the 4 clamps to mount the woofs in the Sovereign and Olympus, and went to 8 tee-nuts behind the baffle instead. The correct way to mount the split ring is on the face/outside of the baffle (which yours is) with the white o-ring on the 075 against the inside of the baffle. You will see some with the split ring incorrectly mounted on the inside of the baffle. From the factory the LE15A was mounted on the side of the cabinet that had the 075. Trivia! Rick