My father used to work for Commer Cars.
They were bought out by Chrysler. ain:
All the years developing an engine that would not intrude into the cab wasted, the TS3 a flat six scavenged by a Roots blower.
Dodge used one of their monster diesels, 140 Db´s in the cab.
Those Commer 'Knocker' diesels were a 2 stroke - hence the noise. They ran 6 pistons in 3 cylinders - 2 opposing pistons reached tdc together and the fuel was injected between them, piston-conrod-'rocker arm'-conrod-crank.
The crankshaft was below the middle of the horizontal bore. They were AWFUL and so unpopular that in their later years Commer Australia had to junk their engines and fit 671n Detroits just to sell their ugly trucks.
Sorry Andyc, your truck, if it's like 73oldsmans photo is much prettier than the cabovers we got here (malc's photo) The superpoise looks like a small K5 Inter, which along with the Reo Speedwagon would be God's truck of choice if he had to deliver fresh bread or fish.