IAR 37, 38, 39
With the first prototype flying in 1937, the Romanian designed and built IAR 37 family was a successful reconnaissance and light bomber aircraft used into the 1950's.
The IAR 37 was designed to use the IAR K14-II C32 engine of 870HP, but problems with engine supply led to production quickly shifting to using the BMW 132A engine of only 700HP. With only minor airframe changes, the aircraft now became the IAR 38.
When the IAR K14 engine reliability issues had been resolved, production was switched to using the IAR K14-IV C32 engines with 960HP as the definitive model IAR 39.