Wow. Model 259. Very strange. I wonder if this is a base, no frills, cheaper 1963 model. Eureka often got rid of parts from 3 or 4 year old models by creating odd models that had partly old components and partly newly-designed components. It's a cheaper, no frills model because it has no bag graphics, no finger switch in the handle and no headlight.
This 259 has the following 1959 components: motor head profile, single piece handle, 1959 brand graphic on the tool port cover. The newer mid 1960's elements are: new vinyl wipeable bag, round handle instead of square, and foot-operated pushbutton switch and white cord (as opposed to the matching lagoon blue cord seen on all blue Eureka uprights and canisters).
Looking under the machine, it looks like the two rear wheels are replacements, and the brush roller is a replacement (it does not look like the original 1959-style Disturbulator).