Purchase a Purolator cabin filter for your truck, it comes with complete instructions.
The 2006 GMC Sierra 3500 SLE with the LBZ 6.6 Duramax does not have a cabin filter.
they do not have a cabin air filter
These trucks do not have a cabin air filter.
The cabin air filter on a 2005 GMC Sierra is changed by removing the cover under the glove compartment and opening the filter housing. The old filter is then removed and a new filter put in its place.
Under the dash on the passenger side.
Remove the glove box door. The cabin filter is in a holder on the left side of the heater core.
They don't have one
In a 2010 GMC Sierra, the cabin air filter is located behind the glove compartment. To access it, you typically need to open the glove compartment, remove any contents, and then unclip or lower the compartment to reveal the filter housing. The filter can then be removed and replaced as needed.
Purchase a Purolator filter. It comes with complete instructions.
The cabin air filters are located in the heater box above the lower panel, mounted below the glove box.drop the plastic panel, 3-7mm screws, then you will see a black access panel, with 1 screw holding it up. the 2 filters are located there. Sorry, I misread the question and read it as 2000 GMC Sierra. Your 2008 GMC Sierra doe not have a cabin filter.
How to Replace a Cabin Air Filter on a 2006 GMC