It is almost impossible to identify a potato digger accurately from a couple photos without having a makers mark or something useful to identify it with. On first blush I would be tempted to say gee ... that looks a lot like my Massey-Harris #1 Potato Digger. I have two of them .. the 2nd one is the same colour as yours. Course that doesn't mean anything. Up here a M-H would be somewhat common, stateside not so much. Could be a JD, IH, Cockshutt, M-M, or could be one of a dozen other orphan lines.
You need to look at it closely and see if you can tell if there is a makers mark or a part number on some of the parts. Is the Tool Box attached and does it have a lid? If so then there may be a clue on the lid. Check parts of the frame and other large parts. The front truck might also have a mark on it. What ever you do don't sell the front trucks -- I did and I wish I never had.
Looks like a nice digger that will work with a Cub nicely