This from Josh Boyajian:

Chicago Fire Department
2016 Ford F-550/Fire Service, Inc.
Breathing Apparatus Service
Quarters: 1044 N Orleans St with 6-4-4 and 6-4-5
Shop #G608
Chicago FD Air Mask Service Unit 6-4-5

CFD Air Mask Unit 6-4-5, 2016 Ford F-550/Fire Service, Inc. Shop #G608. Josh Boyajian photo