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This is a vehicle collection file to spawn a turretless warthog, aka the 'troop' warthog permutation. The troop permutation was left in by Bungie, and is similar to the gauss permutation, except that there are no menu items in the gametype settings to spawn one, it has no turret (No, you can't get into the back where the turret was), and it was never used in the final game.
This file spawns the warthog in the troop permutation just like how the warthog_guass.vehicle_collection file spawns it in the gauss permutation.
The troop hog differs from the regular warthog in that it obviously has no turret, and as it weighs less, goes slightly faster. (Random Trivia: Gauss hog weighs the most and therefore is the slowest.)
This vehicle is really good for racing levels - it has no turret, so you can be sure an idiot won't use it to gun down others, and as I said, it goes a bit faster.
Put the warthog_troop.vehicle_collection file inside your tags folder -> multiplayer -> single_vehicles.
Set the vehicle onto a level like you would any other vehicle, and use the warthog_troop file.
When you play the game, make sure to leave the primary (or secondary) light vehicle settings to Map Default. Otherwise it'll be overridden by any choices you set.
This was a really simple edit; all I did was modify the warthog_gauss.vehicle_collection file and change the permutation sid in the file from 'gauss' to 'troop' with a hex editor. The reason I'm posting this is because most people never seemed to know there was troop permutation.