I photographed these M2 75mm gun examples at Fort Lewis, Fort Lee and Alabama.
These are based on the WWI-era M1897 75mm Gun “French 75” without the tell-tale muzzle rollers at the end of the barrel. Versions of the M2 are named based on the mount, with the later M2A3 identifiable by the spoked crescent-shaped jacks near the wheels. On the page for the French 75, there is an example at Fort Lee of the early gun installed on a M2A3 mount.