The moldings shown on the 1970 340 Swinger in Hemmings are correct for a 1970 340 Swinger. I factory ordered a 1970 Plymouth Duster 340 and the factory order book included the protective vinyl body side moldings as a factory option to replace the longitudinal side stripes. I will also add that my older brother was a car salesman at the largest Chrysler Plymouth Dodge dealership in the Washington DC area in 1970, and his sales materials direct from Chrysler included these exact body side moldings on any 1970 Dodge Dart model including the 340 Swinger. While these protective vinyl body side moldings were not too commonly found on 1970 340 Swingers, these were installed on MANY 1970 Dart Swingers.
If you want more information on factory options for any given year of a Chrysler product, with emphasis on the 1960s and 1970s cars and trucks, you need to visit Barry Washington's website. He is also a member on this site known as Alaskan_TA.
Here is a link to the main page:
The 1970 Hamtramck Registry Home Page
