I need to know how much a rear transmission seal would be to fix.?

I have a 95 Eddie Bauer Ford Explorer that was stolen 2 weeks ago. It has since been found and is in impound. My boyfriend has been saying for several months that the rear transmission seal needs to be replaced and I can't find anyone to give me a price quote without me bringing it up there to them. I don't really want to pay to get it out of impound only to turn around and drop in another couple hundred or thousand! Has anyone had to get their seal fixed? If so, how much did it cost you?