This was originally a UH-1B. The UH-1B had a more powerful engine and a slightly larger cabin than the A model and was introduced in April 1960. Many B models were soon upgraded to C models with a larger and more efficient rotor system. In turn, a small number of UH-1Cs were modified to UH-1M with another more powerful engine and were equipped with night vision equipment and wire-guided missiles. Markings: U.S. Army 174th Aviation Company, Vietnam, 1966