No not a 105mm howitzer mounted on a C47. This is the original term used by the French for their horse artillery (artillerie volante). I had a left over HaT wurst wagon and I remembered seeing a picture of it being used used by the French horse artillery, so that was the idea started.
The figures are the old Airfix Napoleonic RHA figures, not quite correct but close enough. The train driver has had a head swap to give him a bicorne.