What is the M3/75 in La Campagne de Tunisie?

[Blackcloud6]

All US mounted Tank Destroyers in WWII were classified as "Gun Motor Carriages;" this was done to distinguish them from tanks.

The towed guns in the TD units were also "tank destroyers" in the general technical sense.  The reasons they were not "Anti-Tank Guns" were: 1. The "Anti-tank" concept was considered doctrinally a defensive doctrine.  The TD command did not want the TD units, both towed and mechanized, to be considered for defensive use only. 2. The Anti-tank doctrine belonged to the purview of the Infantry Branch; so, the Infantry Center and school formed the AT doctrine and requirements for materiel acquisition.  

However, many sources will call such guns as the M5 3inch gun and "anti-tank gun," the TD Command did not consider it such.