NASA Photo ID: KSC-71PC-0777, S72-30695, AS16-0104-2
Date: 12/22/71

Apollo 16 astronauts John W. Young, right, and Charles M. Duke, Jr., maneuver a training version of the lunar roving vehicle about a field at the Kennedy Space Center simulated to represent the lunar surface. Blasting off for the Moon from the Space Center not earlier than April 16, the astronauts will conduct three expeditions on the lunar surface as command module pilot Thomas K. Mattingly II, orbits the Moon.

Source: NASA issued photo in my possession, can also be found at:
http://images.ksc.nasa.gov