rear end

Hey you guys and gals, out there with all the knowledge. I was at the local Pick a Part today getting a seat for my Father-In-Law's Ramcharger and I happened to see a 1966 Dodge Pick up that was stitting on the rear drums. I stuck my head under it to look at the rear end, cause that is the kinda guy that I am, : O , LOL anyway, it has an 8-3/4 on it. Will that work for an A-Body? Would it have the big bolt pattern, I think it did but not sure. How much work would I have to do to make it work under the Dart for My wife's bracket car. I can get the entire complete rear end, for 100.00 if I pull it. I have no idea what the gears are or anything. Come on don't hold back what is everyone's opinion. I was thinking about buying it and then reselling it too if it wouldn't work.