Douglas Aircraft Series DC-6 and and DC-7C

A pair of early airliners. The DC6 first flew with American Airlines in 1947. It was known as the C-118 Liftmaster by the USAF. The DC-7 first appeared in 1953 and was the last piston engine airliner Douglas made before made the jet powered DC-8.
The 7C was also known as the Seven Seas and had extended range. About 5,000 miles.
The DC-6 was more reliable than the DC-7 and managed to outlast its replacement.