Originally Posted by
John E
Measure the seatpost diameter. If the (presumably) 28.6mm OD seat tube takes a 27.2mm post, you have a butted frame, probably CrMo. A 26.4mm post indicates straight-gauge moly steel, whereas anything smaller suggests cheapo carbon steel.
On a 1970s bike, cottered cranks are definitely a low-end marker, but remember that the 1961 Schwinn Paramount came with cottered cranks and Weinmann centerpulls, as did both of my otherwise high end ca. 1960 Capos.
Yes, before the rise of aluminum cotterless cranks, cotter pins ruled. FB, Magistroni, and Stronglight made some fantastic forged cottered cranksets for racing.