Noise from my car speakers?

I have a 1994 ford explorer, when I got it both front end speakers were blown out, so I replaced them with stock unblown speakers from a 04 f250. The problem is they make a scratchy white noise when I play the radio, but not when I play a cd. Some audio car rookie told me it was my fm tuner box thing thats behind the back passenger seat. So i jiggled a dial or 2 but notice no difference. I'm tired of the annoying ghetto noise, and would like a solution.