When did production of the #13 cab begin?

[Jason Ginn]

The database on the Canadian Register website includes the following examples with relevant dates.

Late 12 cab Chevys:

No. 42 Cab Chev Portee, Model 8440X2 fitted with a 7G1 body, located in Leics, UK.

Build date: Nov 21 - 1941
Chassis number: 1844031825
Engine number: 3742886
Contract: SM2028
Registration number: CL4595318


Late 12 cab Fords:

No. 12 Cab F8 WIRE. Located in Essex, UK.

Build date: Nov 13 - 1941
Chassis number: 21825
Engine number:2G-49525-F
Contract: SM2014


No. 12 Cab F8 GS. Located in Devon, UK.

Build Date: Nov 17 -1941
Chassis number: 21922
Engine number: 2G-49764-F
Contract: SM392


The Database on the OLD CMP website contains the following:

No. 13 Cab Ford F60s 448M. Located at a Sawmill in Daylesford, Aust.

Build Date: Mar 13 -1942
Chassis number: 37206
Engine number: 3G-19676-F
Contract: SM2104

So the Ford changeover was between November 17, 1941 and March 13, 1942 (I am a hesitant to include the Salens truck dated February 15, 1942 without any supporting serial number information), and the Chev change was between November 21, 1941 and January 13, 1942.

Does anyone else have numbers that could narrow the changover windows down?