Head - Rip Cord
Arms - Bullet-Proof
Torso - Airborne
Waist - Cobra
Legs - Gung-Ho

Helmet - Rip Cord
Rifle - Marauder Inc.
Backpack - Low-Light

One project I'm working on is to give each of the original characters a unique look, but still something simple and military. Grunt is the most "generic soldier" of all the original Joes, so his parts were selected to be as basic as possible. The only thing that marks him as unusual is his sidearm, which your typical infantryman wouldn't be carrying. But Grunt is special operations, so it makes sense for him. I also made sure to give him a big pack, so that he'll be humping a heavy load like a real grunt.