To do a through job of it, have the drums checked for size. If they are out of tolerance width wise, usually because they have been cut one to many times (generally .060 over,) then you should replace the drums. It they can take a small cut, you might consider having them machined to make sure they are round. Drums can go out of round, or warped as they use to say, for any number of reasons, cold water hitting a hot drum for example will do it (like driving over a puddle of water right after a rain, and the cold water hits just one hot drum). That will also cause a bad pull to one side. Also, are you positive the front brake lines are clear, hoses in good shape, that none front brake lines is squashed or smashed in, even just a little bit?
