2 guys in the cab Paul, then 2 jumps seats directly behind and if there were extra guys they hung off the side on the steps.
We had another truck just like this one, early 50's LaFrance aerial, and there were full sized oxy-acetelene tanks strapped to the side near the back. Always had a guy hanging on back there and the idea was if the tanks come loose he had to hold onto them....yeah right, while the trucks going down the road at 50-60 MPH.
Thankfully things have changed in the past 50 years.