Do you have a probe in the butt? Resist the temptation to open the door! Take that puppy to 195˚, take it out of the smoker, wrap it in foil and toss it in a cooler for an hour or so. Pull or chop as desired.
That 6#er will take a minimum of 9 hrs and more than likely 12+ It won't be unusual to go 14-18 hrs. Be patient. You'll love the results!