Some of the same stuff is going on today
Look no further than the last line of DD machines from Whirlpool. They are offered in 2.5, 3.2, 3.5, and 4.0 cu. ft. capacity, but to the best of my knowledge, the ONLY machine with a different tub/basket size is the 2.5. The others are all the same physical parts. In Kenmores, each one gets a slightly 'better' agitator as you go up in capacity, but the sheer volume of the machines is the same.
G