Dodge has offered both the Perkins and Mitsubishi diesels in pick up trucks. I once owned one of the Mitsubisihi engines that I bought from a junked truck and have seen the Perkins in a couple of Dodges, but I don't think either was offered before the 70's.
Chrysler had a deal with Nissan years ago to offer the Nissan diesel as part of the Chrysler marine and industrial engine line. I remember seeing one on display at a Chrysler industrial dealers store.
It is entirely possible that there were some experimental installations done in the years before they were offered for sale.