Given that the DC04 yellow/grey was in production for the longest, when all the other DC04 machines had ended production (I do beleive you could still buy these cleaners way into 2003), what I was mean was this was one of the earlier ones as Dyson changed the flex sleeve long befor production ended. But I take on board the comments about the lettering changes.
As for the none-washable filters, there is a bit of a story behind that. The DC01 as we know had a side-filter which required replacement every three months. The DC04 was supposed to be a major advancement on this, with a filter that lasted 12 months. The DC04 went on sale in very late 1998 / early 1999 and up until then the only thing like a Dyson in terms of competiton was the Electrolux Powersystem cleaner, a range of vacuum cleaners which had all sorts of filters.
But at the same time the DC04 went on sale, so Hoover unveiled their Vortex range of cleaners. Not withstanding the fact that James Dyson went on to sucessfully sue Hoover for design infringment, one of the key selling points of the Hoover was that the filters required no replacement.
Within a very short time Dyson had redesigned it's filters, with reps visiting stores to change the filters in the cleaners that were in stock ready for sale, and fitting new stickers to the fronts of the cleaners which stood on display.