This from Larry Shapiro:

Here’s some updated information on the new squads for Chicago.

After receiving the finished units from Rosenbauer America, it was determined that the ‘A’ units with the aerials needed some minor alterations to maximize the maneuverability of boom. As designed, these units had two storage compartments accessible from the top on either side of the body. The rear compartments on each side constrained some of the boom movement. Subsequently, the units have been at Chicago Fleet Services undergoing modifications. The work has been completed on Squad 2A and Squad 7A. Both companies are scheduled to take possession of their new apparatus Tuesday, February 14th. The work is still in process for Squad 1A and Squad 5A.

The personnel at Chicago Fleet Services did a terrific job removing the existing material and fabricating a diamond plate cutout for the boom to swing.