Well just remember, as a Scud missile carrier this center area would have been totally open for the missile to lay into. Also on the largest of the 7310AA-60/70/80 Airport Fire trucks this space contains a large foam tank separate from the water tank. However on the smaller and intermediate size Fire Trucks this area is enclosed with the exact same structure as seen on this 7410 model.
But the smaller Fire Trucks use the exact same enclosure such as seen below. Looks like the roof is hinged to open gull wing style.
