REAR DIFFERENTIAL ASSEMBLY PER GM'S SERVICE BULLETIN NO: 13384 "SUMMARY: THE REAR DIFFERENTIAL ASSEMBLY IN CERTAIN 2014 CHEVROLET CORVETTES WERE SHIPPED WITH IMPROPER FLUID LEVELS. OPERATING THE VEHICLE WITHOUT SUFFICIENT FLUID IN THE REAR DIFFERENTIAL ASSEMBLY COULD PRODUCE A LOUD WHINE AND/OR GEAR OR BEARING NOISE." THESE VEHICLES WERE THEN TOPPED OFF WITH FLUID AND SOME STILL HAD NOISES PRESENT REQUIRING DIFFERENTIAL ASSEMBLIES TO BE REPLACED HOWEVER THE ISSUE PERSISTS. DEALERS AND THE MANUFACTER WERE TELLING CUSTOMERS THE "WARBLE" SOUND THEY HEAR IS JUST DUE TO ENGINE NOISE/VIBRATION AND THE CYLINDER DEACTIVATION. NOW THAT VEHICLES ARE OUT OF WARRANTY THE ISSUE IS THAT DIFFERENTIALS INTERNALS ARE BEYOND REPAIR AND NEED REPLACING. GM HAS CHOOSEN NOT TO ISSUE A STANDARD RECALL, EVEN THE PREVIOUSLY MENTIONED 2014 MODELS WERE NOTIFIED, HANDLED AT DEALERS, AND PUT A STOP SALE ON VEHICLES FOR THE ISSUE BUT THEY ENDED THAT PROGRAM 11/30/2015. VEHICLES THAT EXPERIENCE THE ISSUE WILL COMMONLY HAVE A WARNING INDICATOR SAYING "SERVICE REAR AXLE" OR "REAR AXLE SYSTEM OFF" POP UP INDICATING WHERE THE ISSUE IS. COMMON CHECKS INCLUDE FLUID LEVEL, BATTERY CONNECTION, CONTROLLER/SENSOR PLUG CONNECTIONS AND MORE. VEHICLES THAT EXPERIENCE THIS ISSUE CAN LOSE ABILITY TO CONTROL THEIR VEHICLE AT SPEED OR HAVE THEIR DRIVE AXLES LOCK UP WHILE MOVING CAUSING INJURIES, FATALITIES, AND MORE AVOIDABLE DAMAGES