Head: Custom Cast Part
The Rest: Marauders Task Force Parts

Range Vipers are basically the Forward Observers of Cobra. They are deployed behind enemy lines for extended periods of time. They make their own campsites, catch their own food and steal their own ammo. Range Vipers don't really call for ordinance strikes as they are expected to raid enemy positions on their own.
None of this explains why the heck Range Vipers wear skull helmets with brains on the outside. Stupid!