The GMC S15 rear location accommodates a 4x10 inch speaker size across all listed model years. Compatible types for the audio system include full-range replacement units. These specifications cover the years 1986 to 1989.
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 rear speaker location in the GMC S15 accommodates a 4x10 inch driver across the 1986 through 1989 model years.
A 4x10 inch speaker occupies a rectangular footprint, which differs from the circular cutouts found in many passenger vehicles and reflects the spatial constraints of the S15's rear cabin area.
The elongated 4x10 inch format positions the speaker cone along a horizontal axis, a geometry that affects how sound disperses rearward within the cabin.
The 4x10 inch dimensions indicate a moderate radiating surface area, capable of reproducing mid-bass and midrange frequencies but with reduced low-frequency extension compared to larger round drivers of equivalent cone area.
A rectangular driver such as the 4x10 inch format requires a mounting location with sufficient structural depth behind the panel to accommodate the basket and magnet assembly without obstruction.
Full-range speakers are designed to reproduce the entire audible frequency spectrum from a single driver, covering low, mid, and high frequencies without requiring an external crossover network.
In a rear installation position such as this one, full-range drivers handle both ambient fill and upper-frequency content that reinforces the soundstage produced by front-mounted speakers.
The exclusive compatibility with full-range types across all 4 listed model years indicates the rear location does not support dedicated component configurations such as separate tweeters or woofers in the same mounting point.
Full-range drivers in rear cabin locations typically operate without dedicated amplifier channels tuned to subwoofer or high-frequency-only signals, functioning instead across the broadest possible bandwidth from a single input.
The 4x10 inch speaker format is relatively uncommon in modern speaker manufacturing, meaning replacement or upgrade selection for GMC S15 rear positions requires verification against the specific rectangular cutout dimensions rather than a standard round diameter.