David Heath

i HAVE A 2007 SIERRA WITH THE FOLLOWING TRANSMISSION ISSUES 1.ALMOST EVERY TIME I SHIFT INTO REVERSE THE SERVO ON THE TRANSFER CASE POPS OUT AND MAKES A SERIOUS WHIRRING/GRINDING SOUND. iF I POP IT INTO NUETRAL AND BACK INTO REVERSE EVERYTHING IS FINE. THIS HAPPENS IN 2W AND 4W! 2. EVERY SO OFTEN WHEN I STOP AT A LIGHT OR STOP SIGN AND THEN PROCEED SHE WILL TACK OUT LIKE SHE IS STUCK IN LOW GEAR. I IMMEDIATELY PULL OVER. SHIFT TO NUETRAL THEN REVERSE AND BACK TO DRIVE IT USUALLY FUNCTIONS PROPERLY. 3. RECENTLY I USED 4WHEEL LOW TO TOW A VECHILE. AFTER I WAS FINISHED I SWITCHED IT OUT OF 4L BUT SHE REMAINED STUCK IAND SERVICE 4 WHEEL DRIVE WARNING CAME ON. THIS HAS HAPPEND TWICE. i REPLACED THE SERVO THE FIRST TIME AND ALL WAS WELL UNTIL I USED 4L AGAIN. i HAD TO DRIVE IN 4L FOR THREE DAYS UNTIL MY MECHANIC COULD LOOK AT IT. HE WAS ABLE TO CLEAR THE ERROR CODES AND GET HER TO FUNCITON IN 2W AND 4H. I REGULARLY CHECK MY FLUID LEVELS. NOT ONCE HAS THE TRANNY FLUID BEEN LOW OR DISCOLORED OR HAVE A FUNNY SMELL. ANY IDEAS? MECHANIC SAYS I NEED A NEW TRANSFER CASE. I'M NOT SURE THAT IS THE FIX ALL!