Where can I get a good rear end for A 62'

[62'comingthru089]

I have a 62' with a 350 in it right now i plan on getting a new transmission sometime and want to change the rear gears but I dont know that much about ratios and i dont know if I can just change the gears out or if i will have to get a whole new rear end. I want something that will make my truck badass. I dont care if its out of a car at the junkyard i just would like to know what car or where i could find a decent rear end?

thanks
Jamel