I am sure that the CMP radiator support is derived from the part used on the 1940 (and earlier?) civilian 1 ton trucks. That explains the circular cutout in the angled face at the front top. It was originally to allow clearance for the mounting bolt and wiring for headlights. The part numbers for the supports do differ, as you would expect since the CMP ones are cut offs from the civilian pattern. The cuts don't all seem identical so I wonder whether the CMP supports were originally stamped as civilian parts and individually cut off, all similar but not identical. The C15A parts list gives 3 numbers for the radiator support for different serial number ranges, without the note "when stock depleted use number...." so the differences were of some significance to matching the cab assembly.
As to the radiators, you could take the part number(s) from your CMP parts list and go into the Master Parts Lists at
www.tocmp.com to see if you find a match to a civilian part (probably not before 1938 or after 1942 but stranger things have happened so you may want to check a wider date range). The C15A parts list has 5 different radiator cores, while the C60L parts book lists 6 different cores (the 5 for the C15A plus a special for the 6 pdr portee). The radiators do have the "when stock depleted use number...." note, except for the difference of whether there was a fitting of the overflow tank.