7 1/4 rear flange

I have a 67 valiant and was getting vibrations at certain speeds (40 mph+) and they would get louder as I deaccelerated . Finally jacked it up and as I suspected rear u joint was f- ed up! So I switch both front and rear now the car is freakin smooth! ..... But! The u joint was so fucked that it broke part of the flange where the u joint bushing sits . I was able to seat the joint in well and bolt it back up but. Around 50 mph there's a slight winding noise no vibrations or anything just a bit of low winding. Not sure if the piece that broke off the flange has knocked the flange out of balance wich is causing that winding. My question is how hard or easy is it to change the flange on the rear end . Is it just that big bolt and washer that I have to remove?i found a flange for a 7 1/4 for 30 bux . Wanna find out if I can do this job or is it better to just get a complete rear end since people practically give away 7 1/4's. Any input is appreciated thanks in advance!