Did it happen to come with the yellow and white Sears tractor. As soon as I saw the cart I immediately thought it was a sears due to the triangular shaped toungue in stead of the normal straight. I've never seen a hand crank on a dump cart before so maybe this is a top of the line luxury cart.
On front lower panel of the cart, it looks like you can see where the tag was. Measure that spot, and maybe even rivot hole to rivot hole, and compare it to the serial tag on the Sears tractor which should be by the gear shifter.
Here is a link to a pic of a Sears trailer that is prob the same but without the crank.
http://www.vintagesearsgardentractor...3_dumpcart.jpg
Good luck