[Geoff Winnington-Ball (RIP)]

I have a copy of the original Data Book covering the Valentine and other 'tank-type vehicles of Canadian Manufacture'. It lists the Valentine engine as being a single 'General Motors Two Cycle Diesel 6004 Special 6-71 Series Engine modified for tank use'. It doesn't say where they were manufactured, but David ought to be able to sort that out from his detailed research.

The twin 6-71 diesel powerpack was used in the M4A2 Sherman family but is not mentioned in this book because the tanks were of US manufacture, so I don't know its numeric designation.