William,
Given that you have identified your engine as a 216, a peek at this linked page
ARM, valve rocker extracted from the 1929-57 Chevy Master Parts and Accessory Catalog shows there are 2 different "intake" valve rocker arms for your application. Intake rocker L (left) is shown as GM# 839463 and Intake rocker R (right) is shown as GM# 839464.
Your identified broken rockers are both intake valve, but each is of a different orientation (L and R) so you will need one of each.
Just a word of caution before you dive into purchasing/acquiring parts. Suggest you confirm for sure that the engine you have is in fact a 1953 216. Many in the community will vouch for the fact that more often than not, the engines in our trucks are not the originals. A 216 can very much look like a 235 for 1953. The only way to be sure is to confirm what you have by verifying the casting number on the block (and head) plus the stamped Engine ID number on the machined pad between the distributor and starter.
BTW - The site chevy.oldcarmanualproject.com is free and provides access to a great list of old truck publications for everyone to use when working on our trucks!
Let us know if there is more we can do to help.
