OldCrankman
Scott,
The Dirt Devil brand started in 1984 with a hand vacuum, model 503. It used the exact same belt and brush roll (and the 192 attachment kit, which in this case was optional) as the model 501 Prince all-metal hand vacuum. Royal wanted to get a bigger slice of the retail/big box market share (Sears, Montgomery Ward, J. C. Penney, Wal-Mart, etc.) since their line of all-metal upright and hand vacuums were only sold through their authorized dealers.
Two years later, in 1986, the 503 was reincarnated as the Dirt Devil Plus with the 192 attachment kit bundled in, and a new standard model, the 103, took its place in the entry-level sales bracket. Also appearing that year was the model 523 Dirt Devil Plus, which had a two-speed motor.
1987 saw the arrival of the first revolving-brush upright to carry the Dirt Devil brand, the Broom Vac model 701, which had a bag that was only slightly larger than for their hand vacs. Royal also marketed the Dirt Devil Pro Series line (blue color) for their authorized dealers, which included the model 533 2-speed hand vacuum.
~Ben