8 1/4 rear end pros and cons

frankenduster: The car is a 72 dart I have a 318 in it now and a 904 tranny. However it dosent have enough poop to her. My plans are to make it a saturday night special that can still get me back and forth to work. The 8 1/4 rear end I can get my hands on is only a housing for $25. I can get that now but whats holding me up is will it cost more to put this thing together rather then getting the 8 3/4?