Hi again Clive.
Following is an extract i sourced from a website and I can not recall which one, with a bit of info you may find answer a few questions for you.:-
"Australian Service Use
As noted above, 153 Humber 1 ton trucks entered Australian Army service beginning in 1955. The vehicle ID plates carried the nomenclature Commer, not Humber, and it is believed that this was due to identification of export vehicles. Humber and Commer were both part of the Rootes Group. The vehicles were always known as Humbers in Australian service. The vehicles were given Army Registration Numbers (ARNs) from 105671 to 105823. Interestingly, numbers 105671, 672 and 673, have no details of engine or chassis numbers listed in the Registration book examined by the author in Melbourne some 25 years ago. Perhaps the vehicles were the original trials vehicles, although the ones shown in some trials photos shown Commonwealth (C) registrations rather than Army registrations. The Chassis Numbers noted are all in the series beginning 6310001 with 6310150 being the highest number noted. The chassis numbers are not sequential with the registration numbers.
The original issue of the Electrical and Mechanical Engineering Instructions (Aust) (EMEIs) Data Summary is dated October 1958 and gives the nomenclature as Trucks 1 Ton CT, Humber, Mk1 (Census Code No. 6041). The Data Summaries for those vehicles fitted with radios are dated August 1962, and show the nomenclature as Truck, 3/4 Ton, Cargo, CT, Humber (FFR)"
Phil...