Head: Alley Viper V1 (modified)
Chest: Track Viper V1
Arms: Cobra Commander V3
Waist: Moto Viper
Legs: Track Viper V1

This is an older custom that I posted on the boards a long time ago, and never submitted to the gallery.
I was never crazy about the undersized head of the original Track Viper and had some Alley Viper heads that I was experimenting with. When I put it on the Track Viper chest it seemed like a decent fit. I also had some extra Battle Armor Cobra Commander arms that likewise seemed to fit decently.