Extended cab truck, Montreal, 1939

[landman]

He somehow dropped his load.

[Brian Austin]

Could be a sleeper as well.

[Oldcarfan27]

Too skinny, too short and too open to sleep in. Unless the driver is 4'7", 98lbs and used to sleeping in daylight. 

[Brian Austin]

There were cabs like this offered by various manufacturers in the aftermarket.  Long distance carriers could rotate drivers.  One rested while the other drove.  Note the cab appears wider than stock.  And, yes they often had windows.

 

[Brian Austin]

Coachbuilt.com is a great resource...

http://www.coachbuilt.com/bui/o/orrville/orrville.htm

http://www.coachbuilt.com/bui/c/crown_steel/crown_steel.htm 

(variety of cab types offered)