Crew Positions.... M-60a1 series
Tank Commander (TC):
Commonly referred to as the "TC,"  the tank commander's job is to direct the operations of the tank crew and supervise maintenance. 
Weapons systems:  M-85  .50 cal. machine gun mounted in a cupola on top of the turret.  The TC also has access to the 105mm main gun via the TC overide (seen in the first photo to the right of the commander's right arm).  This overide resembles a game joystick. 
Rangefinding:  Coincidence rangefinder which extends across the top of the turret (the commander in the top photo is using the rangefinder, with his hand on the ranging dial).
Night vision:  in the "Rise Passive," a passive imager is installed, which is the long tube with the green ring.
The commander is also responsible for target acquisition, in which there is little substitute for the old fashioned method.... searching the horizon.
The gunner is buried inside of the turret, without his own hatch to escape.  In an emergency he would have to use either the commander's or loader's hatch to exit.  He could squeeze through the turret ring to reach the driver's compartment, but such was difficult at best.
Weapons systems:  the M-60a1 gunner has his finger on the trigger of the M-68 105mm rifled main gun.  The gunner also controls the coaxial ("coax") M-240 7.62mm machine gun.  Older versions carried the M-219 or M-73 machine guns (both models detested by the crews since they continuously jammed).  On the Rise Passive, the gunner has a passive imager mounted to the right  of his periscope array (seen here near the center of the photo).  Turret traverse is by hydraulic power, with a manual hand crank (seen near lower left) for emergencies.
A few notes about the photo....  the gunner's power switches are at the far lower left (the small toggles).  The eyelit at the bottom of the photo was used to lower the main gun breechblock.  The eyelit was screwed into the block, and a crank was used to lower it to the floor.  The dial at the upper right is to the commander's rangefinder.  Finally, gunners rarely wore headsets, since they provided no protection when being banged around inside of the turret.  Headsets were typically worn only during tank gunnery (to provide a better sight picture).
A few notes about the photo....  the commander's cupola could be rotated and the M-85 elevated.  This was done by hand, and the two cranks are visible.  At the upper left is the elevation crank, and to the far right is the traverse handle.  The elevation handcrank also had a small button for firing the machine gun.