Hey Tim... I have the original pads so that's good to know. So I found a source that lists the Dynacorn bases as replacements for a 69 Buick Skylark and they look the same as Camaro, Chevelle, Cutlass, LeMans armrest bases. The guy that did my interior over lost the DS base and ironically he gave me two PS bases and pads back after covering them with vinyl because he felt the molded plastic didn't measure up to the door panel material finish.
BINGO! Just kept searching and finally came across the OER part number for replacements (OER8769928) and eventually got on OER's web page. Here's the list of cars these armrest bases were used in: