Head - Grunt
Arms, torso, waist, legs - Rip Cord

Helmet - Mutt (accessory pack version)
Backpack - Viper (reproduction)
Machine gun - A-Team

Sokerk was an Argentinian exclusive, though he was not one of the famous "Argen 7" figures. Two version were released: one was a recolour of Grunt (and was essentially a version of "Tan Grunt"), and the other was a recolour of Rip Cord. So to make my version of Sokerk, I repainted Rip Cord's body and added Grunt's head with darker hair, to split the difference.

For those not familiar with the character, here's a translation of his filecard from the original Spanish:

"Sokerk is the Resolute Commandos expert in explosive ordnance and small arms. Able to arm or disarm any weapon precisely and as quick as lightning. But his favourite ordnance is the hand grenade which he can use in his favourite place: in the middle of the action. He has a hair trigger but incredible courage."