Highly Classified - Military Assistance Command Vietnam - Studies and Observation Group. These groups are what most people think of when they thing of Special Forces in Vietnam. The teams were drawn from army triple volunteers, Army, Airborne, Special Forces and teams were mixed with indigenous troops such as Montagnards. 
6 man RT team. From left to right;
1) US point man 1. Wearing NVA equipment and parts of NVA uniform to disguise himself and carrying an AKM.
2) US personnel with STEN gun suppressed. 
3) (Ivan.) US personnel with Chi Com RPD LMG, Sawn off GL tucked in top of back pack.  
4) Indigenous interpreter and second point man with AKM and wearing  NVA uniform and equipment.
5) Indigenous team leader with XM177E2
6) Indigenous rear guard with XM177E2
The standard "Prick 77" radio and KY-38 Nestor secure system are hidden in backpacks. This was a top secret scrambler system that attached to the standard radio. It was rarely carried due to the weight when attached to the radio (over 50lb)  Due to its delicate nature it was carried securely in the back packs.