when im driving forward straight, there is a like a grinding noise noise coming from where the gearbox is?? i thought it was the driveshafts, but wen a mechanics had it up on the ramps, he sed the driveshafts are fine and the noise is coming from gearbox. he said it is the gearbox diff which is broken?? also wen am free-wheeling in neutral it still is making this noise which is gettin louder?? does this sound right or do u think it will be drivershafts?? any help please in desperate need of this getting fixed