I purchased a Carquest Premium dual action pump for my 216 less than a year ago from Advance Auto.
I just checked. They only have the single action pump listed today.
Rock Auto lists the dual action pump but it's listed as "notify me when available"
O'Reilly lists a pump that looks like a D/A fuel pump in the photos but doesn't specifically say that it is.
https://www.oreillyauto.com/shop/b/...e-truck-1950-chevrolet-truck?q=fuel+pump