I know that the brothers in Norway where your C15 came from had three Chevrolet C15's which were delivered under contract S/M 6050, They were once equipped with the "Special Cold Weather Equipment - SCWE".
Now, Contract
S/M 6050 was a British order for Chevrolet 15cwt 4x2 GS Trucks. They were assigned
census numbers Z-5451950 to Z-5455219 (also referred to as "door number"). It seems this was the last order to GM (Chevrolet) for 4x2 trucks. Although they were all built as General Service (GS) trucks, a number of them were converted to other uses after delivery. These conversions included
Truck, 15-cwt 4x2 Machinery , Type " K, Light" and
Truck, 15-cwt, 4x2, A.A. (follow the links to read more).
Combining the available data on C15's from S/M 6050, from the lists above of David, Canadian Register and my C15, we now have a list to help narrow down the range for your truck's chassis number and date of manufacture:
Chassis Serial | Engine Serial | Order No | Date of Mfg | Notes
3 8421 10106 | SR 3 930 465 | S/M 6050 | 30 August 1943
3 8421 20667 | SR 3 910 102 | S/M 6050 | 9 September 1943 | Z1634044 [REBUILD]
3 8421 20752 | SR 3 931 720 | S/M 6050 | 10 September 1943
3 8421 20976 | PR 3 932 058 | S/M 6050 | 13 September 1943 | Z5453378
3 8421 21587 | SR 3 932 053 | S/M 6050 | 20 September 1943
3 8421 26213 | SR 3 935 647 | S/M 6050 | 11 November 1943
3 8421 26521 | SR 3 937 265 | S/M 6050 | 16 November 1943
3 8421 26661 | u/k | S/M 6050 | 1943
Although there is no direct lineair relation between Chassis Serial and Engine Serial, your C15's engine number SR 3 931 593 sits between the engine serials SR 3 930 465 and SR 3 931 720. That means your Chassis Serial may sit between Serials 3 8421 10106 and 3 8421 20752, and if so, would have been built in the first week of September 1943.