No info, but recently saw one very similar for sale. http://www.americanlisted.com/missouri_25/bicycles_7/1970s_hotrod_wagon_60_seneca_mo_16280855.html
I believe that may be a "Moon Wagon". Had one when iwas about six years old. I remember it having a rounder body to sit in, like the shape of a round moon, so I may be mistaken. I do remember the big n little wheels and similar steering. Its been awhile, I just turned 49 a week ago.
Not a Moon Wagon and your right about the round body,,from what I have been able to find out they were made in the late 60's. I found one recently at a yard sale,,the neat thing about these wagons is they had a extra wheel in the back for doing wheelies. HRP
Man does that bring back memories! One of my very best friends who lived two doors down also had one. Ours got stolen from the front yard I believe. One night my buddy Dave Tubbs and I are taking turns pushing each other on banzai wheelie p***es up and down the side walk. My dad happens to come out and starts looking at the Daves Moon Wagon and says, hey this one is ours, it has these special castle nuts I put on to hold the wheels on better. He and Daves dad get in a big ******* match, about who it belongs to. Dave and I keep on playing, not carring who owns it.., still "playing cars to this day".
Notice how the front track/axle on the Moon Wagon is narrower than the rear. If you were pushing someone fast and they took a corner too fast, the ole Moon Wagon was prone to tipping over. I still have a faint scar on my right ring finger from a near tip over on the right side. I put my hand down (at speed) while making a sharp left into our driveway. I ran into my finger with the right rear wheel, and it used my finger as wheel chalk as it skid to a stop.