I used a Cobra Viper vintage to make it.
Vipers are Cobra Troopers with additional infantry training, and better equipment. They are equipped with armored helmets and vests that can mask heat signatures, and assault rifles with built-in grenade-launchers.
Originally, Vipers were to replace the poorly equipped, but highly skilled "Blue-shirts", but it eventually became established that "Blue-shirts" are the basic level soldiers, while Vipers are advanced infantry.