General Motors Truck

[David_Hayward (RIP)]

However, it looked to me as though the back of the cab-over section has been cut away as though the body was removed at some stage. Or cut back.

If it is an emergency vehicle, are those step boards meant for men to hang on and be shielded from the wind/fire by the wings? Also, the wings have the same "molding" as the hood, which suggests that this was a professional modification by probably an officially-authorised coachbuilder.