THE PLT REPORTED THAT PRIOR TO LANDING, THE UNICOM OPERATOR REPORTED THAT THE WIND WAS FROM THE NORTHWEST AT 10 TO 20 KTS & WAS GUSTY. ALSO, HE SAID THAT WHILE ON BASE LEG, HE ENCOUNTERED A SEVERE DOWNDRAFT. HE STATED THAT HE APPLIED PWR & RETRACTED THE FLAPS TO ARREST THE SINK RATE. HOWEVER, THE ACFT SUBSEQUENTLY STRUCK THE GROUND ABOUT 5 FT SHORT OF THE RWY, DAMAGED THE LANDING GEAR, COLLIDED WITH APCH/RWY LIGHTS & SLID ABOUT 170 ON ITS BELLY BEFORE COMING TO REST ON THE RWY. AN EXAM OF THE WRECKAGE REVEALED THAT THE FUEL SELECTOR WAS POSITIONED TO THE RIGHT TANK WHICH WAS EMPTY. FUEL WAS STILL REMAINING IN THE LEFT TANK. ALSO, THE PROP BORE EVIDENCE OF LITTLE OR NO ROTATION AT IMPACT. ABOUT 8 MI EAST-SOUTHEAST AT THE LA PLATA ARPT, THE 1455 MDT WIND WAS FROM 020 DEG AT 5 KTS. THE DENSITY ALT WAS ESTIMATED TO BE 8478 FT.