Being able to lift armored hatches single handedly. Being able to heave shells quickly, being able to sustain awkward positions/apply physical torque during in-field maintenance.Sorry but what do tank crews need a lot of muscles for? Shells weigh below 20 kg camouflage normally is the small size not the big and the heavy lifting is done by mechanics. 155 or 203 artillery is a different matter.
Remember, this is the sixties, the tools they will bring in the field won't be power tools.