Tank
Most modern tanks most often have four crew members, or three if an auto-loader is installed. These are the:
Historically, crews have varied from just two members to a dozen. For example, pre-World War II French tanks were noted for having a two-man crew, in which the overworked commander had to load and fire the gun in addition to commanding the tank. First World War tanks were developed with immature technologies; in addition to the crew needed to man the multiple guns and machine guns, up to four crewmen were needed to drive the tank: the driver, acting as the vehicle commander and manning the brakes, drove via orders to his gears-men; a co-driver operated the gearbox and throttle; and two gears-men, one on each track, steered by setting one side or the other to idle, allowing the track on the other side to slew the tank to one side.
Regiment
The Tank Regiment was found in both Motorised Rifle Divisions and Tank Divisions, with slight organisational differences depending between the two. By the late 1980s, Tank Regiments operating as part of Motorised Rifle Divisions contained slightly over 1,100 officers and other ranks while those operating within Tank Divisions contained over 1,600. A regimental headquarters oversaw command of three Tank Battalions of thirty-one tanks each, typically T-64, T-72, or T-80 tanks although some units used older models, and an artillery battalion of eighteen 2S1 Gvozdika self-propelled howitzers, with some using the older towed D-30 howitzer. Tank Regiments operating as part of a Tank Division included a fifth combat battalion of motorised infantry, identical to those in BMP-equipped Motorised Rifle Regiments. Combat support and combat service support subunits were the same as in Motorised Rifle Regiments with the exception of the antitank missile battery.