About the numbering, etc.
I did some extensive research back in the 80s on Sears cleaners. The prefix 116. is actually a mark denoting upright vacuums (it may also be for canisters, too, I have to go back and check). Also, Marty, your machine was a successor to the BugEye Imperial. It first appeared in about '37 with the all-metal top, then variations of it with painted tops kept appearing right through WWII. A very popular machine. And, Unimatic, your model in one variation or another, was offered as the "B" line for quite awhile. The "A" versions were mostly headlight models with higher AMP motors, though none were very powerful (but seemed to work fine).