Green Eureka
The green Eureka dates from 1975-76 and would be the tail end of the metal base models. I have a Bennett Brother blue book with that model in it.
I don't know the Eureka models very well at all, as by that time Eureka had so many models it was hard to keep track.
As to who was #1 in the USA, I'd say Hoover was for many years, and its a tough call as to who would be #2. Eureka for uprights probably, although when it came to canisters Kenmore was #1 at least until the Hoover Celebrity P/N came out.
Eureka just quietly prospered. Their deluxe machines were very nice, well made and durable, but when they introduced the blender motor 1400 series their quality slipped.