What size speakers are in a 1988 GMC Sierra?
The typical factory configuration for a 1988 GMC Sierra front speakers is 4x6 inches, with rear deck speakers often sized at 6x9 inches on extended cab models. Exact sizes can vary based on cab configuration and trim, so check your specific truck to be sure.
The 1988 GMC Sierra sits in GM’s late-1980s C/K pickup lineup, a era when speaker sizes were largely dictated by cab layout and radio options. While many base setups used compact, space-saving speakers, optional or upgraded packages could shift sizes slightly. Accurate sizing depends on whether your truck is a regular cab, extended cab, or has a factory or aftermarket audio system installed.
Common configurations and sizes
Below is a guide to the sizes you’re most likely to encounter in a 1988 Sierra, noting what each location typically used. This list reflects common factory configurations and can help you plan replacements or upgrades.
- Front-door speakers: commonly 4x6 inches (about 102x152 mm). Some variations exist with 5.25-inch speakers in early or customized setups.
- Dash/main front speakers: often 4x6 inches, though a few installations used 4-inch round units depending on the radio and trim package.
- Rear deck/shelf speakers (extended cab): typically 6x9 inches, providing fuller rear fill if the cab includes a rear seating area.
Keep in mind that actual sizes can vary by exact model, trim, and any aftermarket changes. If you’re planning a swap or upgrade, verify the openings and mounting depth before purchasing new speakers.
How to verify the exact size on your truck
To confirm the precise speaker sizes for your specific 1988 Sierra, follow these practical steps. They help you avoid buying the wrong dimensions when replacing or upgrading your audio system.
- Inspect each speaker location (dash, doors, rear deck) and measure the opening width and height to determine the likely size (for example, 4x6 or 6x9).
- Remove one speaker grille or panel carefully and check for size markings on the speaker itself or a label on the mounting frame.
- Consult the vehicle’s original equipment specifications or a factory service manual for the exact size by trim and cab configuration.
- Consider the cab type (Regular/Standard Cab vs. Extended Cab) as that often dictates whether rear speakers are present and, if so, their size.
Aftermarket options are widely available, but starting with the correct factory sizes ensures you choose compatible components and avoid fitment issues.
Summary
In most 1988 GMC Sierra models, you’ll find front speakers around 4x6 inches, with rear deck speakers commonly 6x9 inches on extended cabs. Sizes can vary by cab configuration and any aftermarket alterations. To ensure an exact match, measure the openings or consult the vehicle’s service manual, especially before purchasing replacements or upgrades.
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