grinding

have 2000 bravada and wife came home today and said there was a grinding noise coming from front, sounds like something came loose in brakes, but brakes were fine. found leak where driveshaft enters differential, checked fluid and was pretty dry, filled it up and only went to the end of the block and grinding was still there. she said she drove it about 3 miles like this. i'm guessing that the differential is ruined? any ideas on what one will cost and where to find one? are they rebuildable? i've never had any exp
erience with differentials. need advice and help soon. thank you. when they say differential carrier do they mean the whole unit?

Sorry about your differential but it is repairable..
The carrier is an assembly containing the ring gear, differential case, support bearings, axle retaining clips, pin that keeps the axles seperated in the carrier(I forget what it's called) and spider gears. If the ring gear is hurt, the pinion shaft w/bearings, seals and crush sleeve will need replacing too.
Sorry but I don't know the cost although there's Pros who frequent here who could offer some idea of cost