The GMC C/K Series Pickup D-Pillar location accommodates a 4x6 inch speaker size. Full-range units represent the compatible replacement type for the audio system. These specifications apply to the 1994 model year chart.
A single driver that reproduces bass through treble without a separate crossover network. It is the simplest replacement option and is common in factory audio systems.
Additional Notes
The D-pillar location in the GMC C/K Series Pickup positions speakers within the rearmost structural column of the cabin, placing audio output toward the back of the passenger compartment.
A 4x6 inch speaker footprint occupies a moderate surface area, fitting within the constrained mounting space typical of a D-pillar panel without requiring significant cavity depth.
The oval geometry of a 4x6 inch driver produces a wider horizontal dispersion pattern relative to a circular speaker of comparable area, which influences how sound projects across the rear cabin space.
The GMC C/K Series Pickup D-pillar accommodates a 4x6 inch mounting cutout, a dimension that determines the maximum cone area and therefore the low-frequency displacement capability of any compatible driver in that position.
A 4x6 inch speaker in a rear pillar location handles ambient and fill-level audio rather than primary directional sound, given the distance from front-seat listeners and the angled mounting surface of a D-pillar.
Full-range speakers reproduce low, mid, and high frequencies within a single driver assembly, relying on one cone and sometimes an integrated tweeter to cover the audible spectrum without requiring an external crossover network.
In the D-pillar position, a full-range driver handles the entire frequency spectrum independently, which is consistent with locations where dedicated component systems or supplemental subwoofers are not installed.
The 4x6 inch form factor limits cone excursion and radiating area, which constrains bass extension in the lower frequency ranges relative to larger diameter drivers, making full-range coverage more practical than a woofer-only or subwoofer designation in the same space.
D-pillar mounting surfaces are generally angled and integrated into trim panels, so speaker depth clearance behind the mounting face is a relevant physical constraint for any driver installed in the 1994 GMC C/K Series Pickup at that location.