Re-read your location; G'day Matt!
Go to "Gleaner R62 photos". second row of photos.
What we call [ in Australia ] an" ammo box" ex WW2 vintage is mounted as a good solid tool box on the back of the header for very quick and immediate access when dismounting from the cab.
A fair bit of thought originally went into the location and it has stayed in that location through a series of the various Allis / Agco headers / combines for well over 3 decades past.
The piece of 8 or 10"auger tube alongside carries the pressure water fire extinguisher for a first grab in case of fire.
Another foam extinguisher is mounted just outside of the engine bay door at head height where it can be grabbed from within or from outside of the engine bay if there is a fire in the bay and another foam extinguisher is mounted just outside the cab on the outer panel of the grain bin again for fast access in case of fire.