[David_Hayward (RIP)]

The casting number quoted appears, and I repeat appears, to be a Cylinder Head casting number, and the date would appear to be 1942 at leasr...I have only ever come across this one once before..WR 3808775 Head cast 839253 Dtae code C 5 2 March 5th 1942. This could be the original head off the original engine.
The casting date code appears to be I 1 9, i.e. September 1 1939, which makes it a very early Canadian 1940 Truck right hand drive unit although production of 1940 Models did not start until October 20 1939. On the block there should be a block casting number plus a date code.