Blown Differential

I have a 1992 GMC 1500 4x4 and i blew the differential the other day. Anybody know how much work it is to rebuild or should i just take it to a mechanics shop?

I doubt its blown. Drop it down and check to see if all the gears still have lube, teeth, etc. Do it yourself if you dont want to pay the money( expensive, expensive, expensive) go to a junk yard and take off the case and check the gears once again, they are just as good and will work.