Both of these postcards show a Delta DC-7 with different livery (color scheme). And, except for the livery, they both feature the same photograph. Whoever did the retouching was really good. These are from the mid- to late-50s. This particular DC-7 was “written off” in 1962, after a service of eight years.
On the back: “Delta-C&S Air Lines Golden Crown DC-7’s are world’s fastest airlines. This luxurious transport, seating 69 passengers cruises at 365 miles per hour at 25,000 feet, has a top speed of 410 miles per hour.”
The card was printed by Delta and included in folders presented to passengers upon boarding. The flight attendant would mail this card for you at no charge (I think). All you had to do was address the card and scrawl something banal as a message.