Differential Question

Yeah I looked at getting a whole 3rd member assembly to. They used to be just laying around my local salvage yard. People took them out trying to find a sure grip and once they saw it was an open differential and highway gears they just left it sitting. I went back to that salvage yard a week ago and could not find one 8 3/4 in the whole place. They used to have at least 40-50 mopars in the back, no they are all gone. I found 3 cars i would consider old mopars. None of them had anything I could use on them. I can't find anything local as this was my main source of parts in the past. Now I'm left with ebay and paying higher prices. Any help would be appreciated. I just want to make sure that my idea will work before buying all the stuff to do it. Thanks!

Dan