A loud clunky click sound, almost like engine has no oil.

I had to pull a friend out of a snowy ditch and afterwards on my drve home from town, my truck started making a loud clicky clunk in a repetitive sound. All stanges of my 4x4 shift and work fine. All my gears shift and work fine. The enginemakes the sound in idle and really intensifies when pressing the gas. I can feel the clicking when I touch the left hand side of the engine (opposite from where you put oil in) all of my fluids are good, no specific overheating anywhere my rpms look normal no smoke or smells emitting, what may this be?