[maple_leaf_eh]

The old Shermans were Militia vehicles and were intended only as D&M trainers and gunnery platforms. The early 1960s were a period when National Survival training was all the rage for Reserve units. The C42s were installed in trucks and CPs as mobile supports. Even into the 1970s the units had those crap radios in big wooden chests for ground mounts.

There is likely a definitive answer, but my supposition is the No.19 sets were never replaced in the Shermans. Too many other priorities.