that is the D&M design that i remember as a teenager. my aunt had one from sears that had the top rotorack so the top sprayarm was replaced by a tube that mounted to the back wall of the dishwasher about a foot long i think. the hose coming down along the left back wall of the dishwasher was the same. angled jets of water from the tube made the top round rack revolve and i remember you could hear it sqeaking as it turned. i used to love to open the door to see that rack whirling around, it got going pretty fast!
at the same time "modern maid" had the same design (d&m) in their machines only the rotorack was replaced by a traditional rack like the one in the above picture and the spray tube was replaced by the top spray arm. same hose coming down back of tub etc.
they cleaned well i remember, but the round top rack of the sears brand was definately more fun, especially at parties! i bought one used in 76 while a student at O.S.U. and it was a big hit when we had parties! everyone wanted to see that top rack turning!!!!!!!