How much wrenching does it take to change them out?

 

not too horrible, mostly a matter of putting it back together the same way you took it apart, depends on if you do just the joint or the whole assembly, if you decent with a wrench and a good do it your selfer your looking at about 4 to 5 hours if everything good smooth, not difficult however a bit time-consuming. shop will charge you about 900. just remember if you dont do it right you take the chance of having differential issues. a haynes manual will walk you through it pretty easly