I have the Scott-Atwater accessories catalogs for 1954 up, and shows these items in there. Quote from write-up:
All Scott-Atwater "Bail-a-matic" models for 1954 are equipped with snap-on connections to permit installation in seconds. It also shows these for other years to. In looking at your 2 lever control box, I would agree this design is from around 1960 as Callie30R states. Earlier single lever control box had a cable and clamp to the middle of the lever. This equipment your showing looks like it fits a Bail-a-Matic model at least from 16 hp up minimum.