Cletrac noted: "It also looks like the soldiers behind the cab have seats there."
I do not think that this is the case. I believe the soldiers in the photo are sitting on the spare tire. Jerricans have been tied in place on top of the long tool box and form nice foot rests.
Here is my old C15 given the same treatment.
This truck is now in the Canadian War Museum in the most prominent position - on top of the bridgelaying tank! It also appears in a Canadian War Museum photo taken at Vimy House and still in use on the web at the Lincoln and Welland Regiment Museum. Old Bill is second from the left. Unit serial 37/1 for the Seaforth Highlanders of Canada.
For the record, the WD number on the doors is ORIGINAL (though repainted) Z5453378 The other markings are authentic but as this truck went through a British Army rebuild in 1948 all other markings were erased so its British Army use is unknown. It is an example of CMPs built for the British. It was donated to the CWM by Brian Wood of Vancouver, BC.