"Did they ever find the bodies of the two soldiers who fell into the river with full packs on and were swept under the water? " Those Marine Seebees didn't fall into the river. Their goal was the enter and wade across the river to achieve an objective.
From what I read, due to the weight of their equipment, they couldn't keep afloat and drowned.
Yes their bodies were recovered.
They were not SeaBees, they were Marines. SeaBees are in the Navy. They were Cpl. Evan James and Sgt. Brad Korthaus of Charlie Co, 6th Battalion, 4th FSSG, a reserve unit out of Illinois.