What size speakers are in an 89 gmc sierra?
The typical factory setup for an '89 GMC Sierra is front-door speakers measuring 5.25 inches, with a dash-mounted 4x6-inch speaker; rear speakers, if present, are usually 4x6 inches. This article outlines common configurations and how to verify your specific truck.
Exact sizes can vary depending on cab configuration (Regular Cab vs Extended/Crew Cab), radio options, and any aftermarket modifications. To ensure accurate replacements, verify with your truck’s build sheet or by measuring the openings directly.
Factory speaker sizes by location
Below is a breakdown of the sizes you’re most likely to encounter on an '89 Sierra. Use this as a baseline, but always confirm on your specific vehicle.
- Front doors: 5.25 inches (approximately 133 mm) in diameter
- Dash: 4x6 inches (typically a 4x6-inch speaker) mounted in the center dash area
- Rear seating area (Extended/Crew Cab or rear panels): commonly 4x6 inches if present; some regular-cab trucks may have no rear speakers
In practice, many regular-cab trucks from this era shipped with only front-door 5.25-inch speakers and the dash 4x6-inch speaker, while extended or crew cab models often added rear speakers of the same 4x6-inch size. Configurations could vary by trim level and radio option.
How to confirm the exact setup on your truck
To verify your particular vehicle’s speaker sizes, use these steps:
- Remove the door panels and measure the diameter of the factory cutout to confirm 5.25 inches.
- Inspect the dash area and remove or lower the dash grille to measure the center dash speaker (likely 4x6 inches).
- Check rear cab panels or the rear wall (if your truck has extended/crew cab) for any additional speakers and measure their diameter if present.
- Consult the vehicle’s build sheet or the original radio/speaker option codes (RPO codes) to confirm OEM equipment and speaker sizes.
Verifying with these steps will ensure you know the exact sizes for your specific truck and help you plan replacements or upgrades.
Cab configurations and options
Different cab styles (Regular Cab vs Extended Cab vs Crew Cab) lead to variations in speaker placements and availability. Some base models may omit rear speakers entirely, while higher trims or specific radio packages may add them. Always confirm with your actual vehicle configuration.
Aftermarket replacements and installation tips
When upgrading, you’ll commonly encounter compatibility with 5.25-inch front door speakers and 4x6-inch dash speakers. If installing larger or different sized speakers, you may need mounting adapters, harness adapters, or a new head unit that supports the revised speaker layout. Always verify physical clearance and impedance compatibility with your head unit and amplifier if equipped.
Summary
For an '89 GMC Sierra, expect 5.25-inch front-door speakers and a 4x6-inch dash speaker in most configurations, with rear speakers (usually 4x6 inches) only in extended/crew cab models or as an optional upgrade. Since configurations varied by cab type and trim, the best approach is to verify by measuring the openings or consulting the build sheet. This will ensure accurate replacements or upgrades and optimal sound quality.
