From Halopedia, the Halo wiki
The M-100627 is a six wheeled vehicle and features bars on the front windows of the vehicle. It can attach a trailer to the rear, or carry cargo on its own.
The M-100627 is an unusable scenery object on the level Winter Contingency. A drivable, modified version of the M-100627 named the ONI Van was made available for the Halo: Reach Forge in the Halo: The Master Chief Collection version of the game.
On the driver's side door of the M-100627, there are what appear to be four victory marks of an Unggoy silhouette. Implying the driver of the truck killed four Unggoy in with the truck.
List of appearances