In GTA III, it's based on a Kenworth W-900, while in Vice City it resembles a Peterbilt 359. The GTA III rendition is seen as a wreck in Denton's Junkyard. The Vice City rendition is seen found in Manhunt 2 at the gas station and at the warehouses.
Manhunt 2 Edit
In Manhunt, there's a bottle of Painkillers inside the container connected to the truck. To get to it, Cash must climb a ladder behind that container.