mark kulaga

I HAVE A 2004 TAHOE 4.8 ENGINE WHEN DRIVING IN 2 HIGH IT WILL GO INTO NEUTRAL COASTED OVER TO THE SIDE OF THE ROAD OPEN DOOR COULD HEAR A LITTLE NOISE NOT LOUD GRINDING MORE LIKE A LITE GRINDING NOISE COMING FROM TRANSFER CASE I BELIEVE HOOKED UP MY FRIENDS SCANNER TURNED TRUCK OFF PUT IN PARK START TRUCK PUT IN 2 HIGH TEST DROVE WITH SCANNER TO DUPLICATE PROBLEM NO CODES ON DASH OR SCANNER ENCODER RING OR ENCODER MOTOR ? TRANSMISSIOM IS FINE IF I DOWN SHIFT 1 GEAR DOWN IT WILL ALSO GO INTO FREE WHEEL OR NEUTRAL ANY HELP THANKS MARK KULAGA