Congratulations on your great B-8 bargain! Please post some photos of your Model B-8 Double Insulation Polisher when it's all cleaned and polished and let us know how it works! Happy scrubbing, polishing, and carpet cleaning!
The full history of the unit, as far as Electrolux USA is concerned, is not known for certain. Some claim that they have heard of a B-3 machine but aren't sure about when it was manufactured or if there was ever a B-1, B-2, et cetera, until the B-6 in the 1950s. These would have been imported from AB Electrolux in Sweden.
What is known is that Electrolux USA's first machine was the B-7 which debuted in early 1959 in the colors of the Model F and Model R cleaners. (Many call the former Model AF, but it was only designated as such on the embossed nomenclature on the machine--as the label had just been revised from the Model AE's as a money-saving measure. If you look closely you can see that the "F" was placed over the "E"--the point being that there was no non-automatic F as there was in the Model E and AE's case). But I digress.
B-8 Variations: reset button on early units; lettering on early units standard block--later units serifed; starbursts on 1963 shampoo tanks--then same gold and white label used through late brown units, then updated with block lettering and brown background color, and the gray units used the same style with silver, white, and black colored labels; removable cord from unit from tan units to gold units--then directly wired; metal brush centers (older)--plastic brush centers (since at least gold units); shampoo tank caps: aqua (aqua units), tan (tan units), teal (teal units), ivory (gold & brown units), gray (gray units); power cords: ivory, teal (aqua units); ivory (tan units), teal (teal units), ivory (gold & brown units), gray (gray units); storage trays, splash guards, handle locks, and handle grips: teal (aqua units); ivory (tan units), teal, ivory (teal units), ivory (gold and brown units), light gray (gray units).
Here is the list of Electrolux USA polishers (aka Carpet Beautifiers, as Floor Beautifiers with the B-9 and B-10, and as Floor Pros with the Model 1522, 1732, 1739, S105s and S165s):
1959-1961: B-7 (gray/ivory; T handle)
1961-1963: B-8/Carpet Beautifier (aqua; T handle)
1963-1966: B-8/Carpet Beautifier (aqua; V handle)
1967-1968: B-8/Carpet Beautifier (tan; V handle)
1968-1974: B-8/Carpet Beautifier (teal; V handle)--yours is from this era
1974-1978: B-8/Carpet Beautifier (gold; V handle)
1978-1982: B-8/Carpet Beautifier (brown; V handle)
1982-1983: B-8/Carpet Beautifier (gray; V handle)
1983-1984: B-9/Floor Beautifier (gray; curved plastic handle; cord winder)
1984-1987: 1522/Floor Pro (sand/jade; curved plastic handle; cord winder; w/Diamond J label)
1987-1988: B-10/Floor Pro (sand/taupe; curved plastic handle; cord winder)
1988-1989: 1522/Floor Pro (navy/white; curved plastic handle; cord winder)
Years Uncertain:
1989-1990: 1732/Epic Floor Pro (navy/white; curved plastic handle; cord winder)
1990-1992: 1739/Epic Floor Pro (navy/white; curved plastic handle; cord winder)
1992-1994: S105A/Epic Floor Pro (navy/white; curved plastic handle; cord winder)
1994-1996: *S105B/Epic Floor Pro (gray/fog); curved plastic handle; cord winder
1996-1998: *S105B/Epic Floor Pro (charcoal); curved plastic handle; cord winder)
1998-2000: S105G/Epic Floor Pro (pastel blue/white; curved plastic handle; cord winder)--75th Anniversary Edition
2000-2002: S105J/Floor Pro (pastel blue/white; curved plastic handle; cord winder)--brush graphic used for O's
*Note: There were two different colors of S105Bs for some reason.
Aerus Label:
2003-2006: S105L/Floor Pro (pastel blue/white; curved plastic handle; cord winder)--brush graphic used for O's
2006-2009: S105N/Lux Floor Pro (pastel blue/white; curved plastic handle; cord winder)
2009-2013: S165A/Lux Floor Pro (white; curved plastic handle; cord winder)
2013-present: S165B/Lux Floor Pro (black/white; curved plastic handle; cord winder)
PLASTIC-BODIED POLISHERS/SHAMPOOERS DESIGNED AT ELECTROLUX CANADA LTD. (1984-1992):
Model 2101 (sand/jade; beige/taupe; beige/navy--matching the Hi-Techs and Diplomat)
Model 2101A (Regency Series: sand/pastel blue and Special Edition: beige/burgundy)
I don't know if anyone collects polishers/shampooers, but Electrolux alone has plenty of different colors and styles to do so!