During the Vietnam War, a standard US Army "Armor Battalion" (tank battalion) consisted of approximately 57/58 Patton M48A3 tanks. Two or more, but usually three, battalions equalled one brigade. Two or more, but usually three, brigades equalled one division. US Marine Corps tank battalions (in Vietnam) were organized the same as the Army's.
Only Army & Marine tank "Battalions" were in Vietnam; as well as armored cavalry squadrons, which were the equivalent of battalions (but contained far more armored vehicles in their troops (companies are called "Troops" in the cavalry).
With the one exception of the 11th ACR (Armored Cavalry Regiment) which, in the cavalry is equivalent to a brigade. In Vietnam, the 11th ACR was commanded by COL. George S. Patton, son of WW2 Gen Patton.