This nozzle would be part of the package for a Class 125 Fire Truck equipped with Hardie High Pressure pump. The application for this truck was Airfield Crash truck.
I own one of these which was originally stationed in Bangor ME. It is in the process of restoration which has unfortunately stalled at the moment.
The nozzle you have has been slightly field modified.
42 Chevy 125 Crash Truck from Dow AAFB, 44 Chevy 325 Crash Truck, 42 WC-54, 44 M29C Weasel, 45 CCKW 353 A2 Air-portable, 44 Case VAIW Tug, M-5 HST, 42 M-10 Ammo, Steel & Wood Ben Hur, 43 Sperry AA Searchlight, 41 Wehrmacht Trailer, PE-95G, PE-99B