I'm not a huge car guy but this used to happen in my yota cause it has a cable to the rear brakes that locks up. Lube whatever ya can along that cable line/ Try not to park with the parking brake on as much or in cold weather/ when all else fails(that other stuff should work) get out after you take off you parking brake and go around to the back of the truck kinda under or behind the rear axle there should be a cable running between the rear wheels that is the brake cable line, I just reach up and pull on that sucker. That used to unlock mine usually. Mine was a yota so this may be different on your truck, like I said I'm no mechanic.
Seriously the way America pines over celebrities makes me ill. It's life, lives end all day. Yeah, sad, a kid died. How many kids are dying all over the world due to far more sinister negligence? Nobody seems upset about that, but when a wrestler dies, oh snap the gloves come off and its hardcore emo crying time. Lets all wear black bandanas and listen to dashboard for a week until the next American idol is voted in and we forget all about that poor schmuck from last week.