Trailers add important capacity for cargoes. This photos also shows the mess trailer.
I have an M47 without a barrel. It got broken and I got it in a used collection. I save it for a potential project. It may become a howitzer version, ARV or maybe even get a main gun upgrade.
Typically several trucks in the battalion will have a ring mounted .50 caliber machine gun for anti-aircraft defense. Vans are used for small item repair or in this case, fire direction for the artillery.
A tank battalion with attached artillery is a lot of vehicles.