That's a "honey" of a vintage Hoover (its color names are pale honey and rust brown). The Concept series is considered by many collectors to be Hoover USA's all-time best performance cleaner.
The U3109 was a basic department store model produced from 1980 to c.1986; although there was also a U3109-100 with a slightly altered color scheme and a different bag jacket pattern. The variant may either have succeeded the U3109 before 1986 or they were sold concurrently. I'm not sure of the extra or upgraded feature that the -100 suffix indicates, but it may be equipped with an air freshener compartment. I couldn't tell from Hesco's schematics.
Btw, the color scheme and vertical brush strokes bag pattern of the U3109 appear to be a match to the Convertible U4309. See thread 43777, that was posted on 9.18.22. It may be the the two cleaners were sold side by side.