Ok so in my 96 250 my parking break light will NOT go off and it makes it a pain in the buttox to even try and drive because while this light is on my break pedal is hard as a rock and i've got to push like hell to get it to stop. I've even had to use both feet to stop before.
So what is happening that would be causing this?

 

Sounds like a bad vacum pump or brake booster.

 

Vacuum pump

 

Alright so one of those two then. How much do these parts run and how much of a pita are they to put in yourself