Originally Posted by
MrBernoulli
Assuming a photo hasn't been 'flpped', a quick way to visually tell the difference between a C-47/Dakota and a Lissunov 2 is the main passenger entrance door. On the C-47/Dakota the passenger entrance door is on the left-hand side of the fuselage (integrated with a side-hinged cargo door, which the DC-3 did not have); on a Lissunov 2 the passenger door it is on the right, with a top-hinged cargo door on the left.
Some earlier DC3s had the passenger door on the right side. It was a customer option. American Airlines main DC3 fleet was built like this, to suit their existing Ground Support Equipment, and others too. There were even a few right-to-left conversions done later. Described here :
The Right Side Door — FLAGSHIP DETROIT FOUNDATION