M39s

The M39 is a designation that has been applied to several different military vehicles and systems, primarily by the United States. The most common association with the M39 designation is the M39 Armored Utility Vehicle, a halftracked vehicle developed during World War II. This vehicle was based on the M3 Halftrack chassis and was designed for various utility roles, including carrying troops, towing artillery, and serving as a command vehicle. It featured an open-top design and was armed with a .50 caliber machine gun. The M39 saw service in the latter stages of World War II and in the Korean War.

Another notable use of the M39 designation was for the M39 3-inch gun, an anti-tank gun developed by the United States during World War II. While it was developed, it did not see widespread combat deployment as more effective anti-tank weaponry became available. In later years, the designation M39 has also been informally or unofficially applied to certain components or modifications within the US military, though these are not official standardized designations. The context in which "M39" is used is crucial for understanding its specific meaning.