Does anyone out there know if the headlamp on a 2006 trailblazer has one bulb (like my civic) or are there two bulbs - one for high beam and one for low beam? I have searched a little but have not found a difinitive answer. Also does anyone know if they are easy to change out? We just bought ours back in Oct and this will be the first time I have had to change one. I am thinking about the Sylvania Silverstars for the TB. I have them for my civic and love them any opinions?