Hi Kelly,
D&M stands for Design & Manufacturing; you will hear of them a lot when it comes to vintage dishwashers. Kenmore was one of the brands that were D&M-made. Personally I think D&M machines are great dishwashers to have; my grandmother had a Kenmore 18" model (since replaced with an 18" Roper which is basically the same except for a plastic tub) and the motor had a very unique sound to it. And instead of filling with the motor running like our GE-design Jenn-Air did, it filled, paused for a short time, then all of a sudden it started up with full force. You could hear the glasses clinking around as well; something I never heard with our Jenn-Air.
--Austin