Sounds like something is off balance

Had a chevy 1/2 ton that made a rubbing noise. Nothing in the brakes and never really got any worse. Decided to pull diff carrier and check it.
A carrier bearing was pitted. It made the noise for years.
It would be a good idea to pull drums and have a good look,making sure e-brake isnt partially on or a sticky wheel cylinder.
Hot drum is a good indicator too.