There are three different mountings on Cessna sumvisors. One, mounts with the screws and brackets and pivots outboard, another mounts with the screws and brackets in the middle of the aircraft. and the third mounts with a bracket in the middle of the sumvisor
The middle of the visor mount was used on later aircraft (ie. mid '80's models) but may not have been used on 150's. Early 150's (pre-'70's models) have the outboard mounting, while (according to the IPC) '70's models have the center of the aircraft mount.
Its confusing so make sure you get or are ordering the correct item(s).
Charles