Thank you gentlemen.
You're welcome Paul and thanks for the info. Just recalled seeing them used in Vietnam too on the backs of trucks in a ground role.Thanks Andrew. They are Maxon M45 gun mounts. M16 halftracks, M50 trailers, & ground mounts were standardized. I believe there were other field expedient mountings, as they were self powered and compact.
For FULL Forum access you can upgrade your account here UPGRADE