In the mid to late 50s, KA and WK were the only brands that used a wash arm, but they were not related in any other way. Notice how both racks' rollers ride on the same rail. That is a neat innovation. At the time, KA had the wash arm with the big spray openings that created "six moving walls of water". The WK had many smaller holes that were angled off in a way that let them show the glasses loaded in the top rack over the serving dish that's tilted in toward the center in the lower rack. Unlike the KA racking then and for decades to come, the center of the lower rack was an open area to help the angles of the spray pattern reach items in the top rack from below. Waste King also switched from a porcelain tank to a Plastisol-coated steel tank within the first couple of years of production, while KA stayed with porcelain tanks for decades. Waste King was also one of the first dishwashers, along with Hotpoint and Kenmore, to have a dedicated water source for the upper rack. In their first portable, the lower wash arm was half the width of the lower rack with a tower in the middle and then the other half of the wash arm was placed under the top rack, sorta like a Z with the middle perpendicular to the top and bottom halves. It took KA until the 18 series introduced in 1977, to have a dedicated water source for the top rack. I read the obituary of the man who headed the company for many years and he was a great philanthropist, using his fortune to help many causes. It makes me like these qwirky old machines even more.