Is my differential toast? 2001 LSD with 210k? Fluid is honey colored, dif is hot to the touch and there’s a vibration between 60-80mph only. Nothing before. Shop put a  stethoscope to it and said he can hear the pinion bearing grinding I think? What are my options and is it worth it or is it a wheel balance issue? Fluid was changed at 135 and 30k ish after, both front and rear.