yes they are GMC and Chevrolet Truck doors are interchangeable only the option is what changes from SLT and LTZ are same option package to the LT LS SLE SL denali are same swell Sierra ,Silverado, Tahoe, Yukon Surburban are same NNBS 2007-2013 cadilac is also the same just a bit of luxury body line and trim

located in the rear of the engine.. hard to reach or see…..

Loose connection somewhere. Double check all of your sub wires / speakerwires both going into the speaker and out of the head unit / amp

The electrical connection within my door latch could be the problem of lights and radio not turning off when driver door was opened. Or You need to press the dome light override button that is to the left of the steering wheel. This is with the knob that has all the controls for the exterior lights as well. There are three positions for the dome light switch, on, auto, and off.