GMC Repair: brakes, clue whats, rear brakes

Question
I have 1999 yukon my rear brakes are locking up all the brakes have been replaces all brakes hardware everything  has been changed they are geting heated up and there locking up when brake is put on, have no clue whats up the truck is at coast tire center they have had it for 2 weeks iam trying to find help with this matter just so know all hardware was changed everything in side those drums,,  hopefully you can help

Answer
Hi
Have them check the proportioning valve.
Check the rubber line from steel line to break off block that goes to each side rear.
Have them make sure all springs are correctly installed.
Make sure they installed proper shoes.

It should not be THAT diffucult to locate and fix a brake problem.
I would advice you if they cannot fix this to take it to another shop.
I Hope this helps.