In my opinion, K-Line made some very nice engines, especially just before being taken over by Lionel. Some scale models that come to mind: 1) Boston & Albany Berkshire; 2) New York Central Hudson; 3) PRR/LIRR B6sb switcher; 4) New Haven EP-5 electric motor; 5) New York Central/Boston & Albany 4-6-6T tank engines; 6) Shay logging engine (maybe larger than scale).
MELGAR