That ad is out of the Jackson, MS newspaper. I vaguely remember Sheppard Building Supply, as it was a few blocks from my aunt's house. I think that was one of the places we went when she was looking for a new dishwasher in 1968, but ended up getting it at Sears.
I remember a 70's KM model that was not a roto-rack, standard upper rack/shelf but it had a spray tube under it with slots instead of holes. The slot-openings were meant to direct the water in a fixed spray under that upper rack. Low-end, cheaper than a rotating arm.