The mirrors will interchange however you will have to drill holes in the tops of the doors. The '71-'74 B-body mirrors were secured with two external screws, after '74 the mirrors were secured with a threaded nut and bolt assembly at three locations from the bottom of the mirror. If the passenger side is a remote the control will be located in the center of the dash at the bottom as opposed to the door. As a result the cable is longer, this can be modified however it isn't easy....