I worked on the DC-3’s and C-47’s as an aircraft mechanic. The main differences were that the C-47 had a large cargo door installed on the rear left side of the fuselage and a beefed up floor to haul cargo. Some minor differences that there was a navigators station behind the pilot and there was a plastic dome installed in the top of the fuselage so the navigator could shoot the stars for night time navigation. The DC-3 had a passenger door installed on the right side of the fuselage and a "blue room" (lavatory) installed. It was called the blue room beacuse it was painted blue. In the cargo version, the aircrew used "relief tubes" to pee in at their flight stations. Some of the aircraft had Pratt & Whitney R-2000 radial engines installed while most of the DC-3’s had Pratt & Whitney R-1830 radial engines. Some other differences were that "speed cowlings" were installed around the engines which were more aerodymaic and landing gear doors were installed to fair in the aircraft landing gear wheels when they were retracted. All if this was installed on the commerical version of the DC-3’s. Not an outoboard motor topic, but you asked….. 😉