The front has a picture of the Valiant A body and the Plymouth B body ...
and the back is a description boasting of the quality of these cars.
Chrysler's new 5 year 50,000 mile warranty was a very successful way to re-educate the public about the quality of Chrysler Corporation vehicles. Build quality, especially in the area of fit and quick rust formation, was an issue raised from 1957.
Thanks to Doug "wagonguy" for providing the postcard!