How do you replace cabin filter?

There were two versions of the 2000 2500 pick-up - new body style and old body style. If your 2000 GMC 2500 Pick-up is the "new body" style, the cabin air filter is located in the heater box and is accessed by removing the trim panel under the passenger side of the instrument panel. In the heater box you should find an access panel for the filter. If your pick-up is the old body style it does not have a cabin air filter.