Convertible. The handle bale changed, the tools went in the back of the Convertible. The motor sounds basically the same. The top of the bag slimmed down shortly after Convertible arrived on the scene. It's a great vacuum.
I know there was one made for Montgomery Ward, the catalog #870, which was a self-propelled model finished in a bright gold and off-white color scheme. It was tested and recommended by Consumer Reports in 1976, along with the similar Hoover Dial-A-Matic U6039.