Need a new rear end for my 63 Dart Wagon

So the rear end on my wagon is growling, and It gets louder as I go faster! I had another 66 dart that had a whine in the rear end, I just replaced the rear wheel axle bearings and that fixed it. But this growl is different, and getting scary. yesterday I touched the rear wheel bolts after driving 5 miles and they were extremely hot! It is the 7 1/4 rear end. I'm thinking from what I read it's the carrier bearings. I don't know where those are located, and or how to replace them. would it be easier, and cheaper to just swap in another rear end? I saw this guy on craigslist had a 7 1/4 rearend out of a 75 dart for 100 bucks. Would that fit under my 63 dart? I think maybe the reason why my rear end is growling is because for years I was using some rear wheels that weren't balanced... I will not be doing THAT again any time soon. Soooo anyways if anybody around El Cerrito California has a rear end that they want to get rid of let me know!! thanks!

Paul