Hi Arthur, welcome to Outdoorking.
The Greenfield wheel-drive system, and its layout using the separate forward and reverse clutches with a very long belt, can be found on several US-built machines, including the Rover Autodrive system. I haven't studied the dates but I think Greenfield adopted it after the Americans introduced it.
mudrock had established that his very early HD8 originally had the standard wheel-drive layout as on other Greenfields, and the original owner had modified it to work backwards for unknown reasons. It can be put back to its original condition provided he can obtain some HD8 parts - aside from a small number of holes having been drilled to mount brackets, hopefully no other damage has been done by the temporary modifications.
