LAU-65D/SGM-151 missile pod

The Missile Pod will be a new weapon in Halo 3 that as the name says, fires missiles. However, the difference between the Missile Pod and the Rocket Launcher is that the missile pod tracks vehicles and the Rocket Launcher does not in halo 3 (stated by Bungie in a game interview by IGN)

Trivia

 * It is apparently an 8-shot missile launcher with no reloads, but is able to lock-on to vehicles. It is held in a similar manner to the Chaingun.
 * The Missile Pod could possibly be the M19-B SAM Missile Launcher that was used by Alpha Company and Beta Company.