Thank you very much John. The more I look at other examples, the more I think mine was incredibly modified by a previous owner. The drive unit on yours in similar but not quite the same. On mine the center wheel is flangeless. Also the connecting rods have been made to look like the center wheel is connected but it is not.
If the loco body on yours is diecast it was probably made since 2011. If it's tinplate construction it's probably older, but I can't guess a time frame. I am still researching when Darstaed was produced under the Vintage name.