Buddies and I regularly rode our bikes to the nearby Sears store. Real kart shops were too far for us for regular visits. I don't recall seeing a Dart kart version or Macs and WBs displayed at the Sears store, but could have forgotten about it--I bought all my kart racing items from the local kart shops. I wonder if this was only a catalog item?
Don't remember seeing karts at Sears on the floor either but I seem to remember a fellow telling me that his dad took him down to their local outlet store and purchased a Power Products.
I know JC Penny had mini-bikes on the floor because I used to walk over from the grocery store where my parents were shopping and go drool all over them every saturday morning.
Wasn't it our friend, Jack Canady, whose first AH58 came from Sears? One of my girlfriends worked at Monkey Wards in Melbourne, Florida. They always had a couple of karts in the sporting goods department. She worked there at the time when you could order obsolete engines for less than half price. I seem to remember Homelite KL-100's for about $39.95! Ted