If in the 1970s we would have DC-9s, 737 Jurassics, 727s, Caravelles, Tu-134, Tu-154, Fokker 27, Fokker 28, A300, DC-10, Il-62, An-26, that chinese 707 copy with slow speed, that japanese thingy, the British Tu-154 copy, BAC-1-11, DC-8 etc. Many more choices.
The most common would probably be either the DC-9-30 or 737-200.