Beechcraft Queen Air
Cessna 206 Stationair
Cessna 210 Centurion
Cessna 208 Caravan (should fall in that period also)

The Cessna 208 Caravan didn't fly until the mid-80s, at roughly the same time
the Cessna piston singles went off the market. The other 3 planes all existed
in the 70s.