Dad worked in the engine overhaul shop for American Airlines for 37 years. He worked on the big round piston engines of Curtis-Wrights and Pratt & Whitney. R-1820's to the mighty Wasp Majors of the R- 4360 and the C-W R-3350 Triple compound engine. He also saw the first turbo jets of P&W TJ-3 or J57 in the military world. JT 4 or the J 75 . Both without afterburners of course. Lol. Boeng 707 and Convair airliners ( I forgot what they were designated). When he retired in '75 or'77, he was on a CF6 engine crew. A huge fanjet engine of 767 and the like airliners.
I should think it would have been quite the run to go from DC-3's to 757's.