John, I didn’t know there were such variations in British rear storage bins, I must look into this. I actually don’t have any Shermans with such myself, except the old Matchbox Fireflies. A pending project for me is to gather the Sherman horde and figure out which I’ll make permanently British and American.
The Firefly had them ‘factory fitted’ when remanufactured. Some other Shermans acquired them too. Some units were far better documented photographically than others.
As far as British Vs American, about the only absolute is no M4A3s for the British, & diesel powered (M4A2) ones (they had a different rear deck configuration) in separate British units & USMC only for the yanks. The Americans had a few, as did Zhee Ghermans…