1978-1982 Chevrolet Corvette C3 (late, fastback rear glass) — subwoofer box fitment

What we researched for this specific generation: where an enclosure actually fits, what the factory speakers are, how the factory audio is wired, and which real builds and commercial products exist for it. Confidence badges say how well each figure is sourced — this is research, not manufacturer spec.

Body styles covered: 2-Door Coupe (T-top)

Where a box actually fits

These are researched envelopes, not a guarantee. Measure your own vehicle — the numbers here tell you what to expect, not what you have.

Trunk Likely

Locationtrunk
Outer bounding boxNo change to this entry's real, deliberate finding — the source states outright that a big subwoofer box will not work here and neither will anything but the most compact powered sub. New: the same real, named RetroSound 8" amplified sub (2.75" tall, 100W built-in Class D amp, variable crossover) found for the 1969-1974 companion entry fits this real constraint too.
Known obstructionsConfirmed, not just asserted: this car genuinely does not have room for a standard subwoofer box.

Starting points

Suggested configurations for this vehicle, not prescriptions. Run the numbers in the Box Builder before you buy anything.

Budget

SubwoofersSkip the subwoofer — the source suggests rear speakers with solid bass performance may be enough, since you sit very close to them in this car
Box typenone
Locationrear quarter panels

Enthusiast

SubwoofersThe most compact powered subwoofer you can find. The source rules out anything larger
Box typecompact powered enclosure
Locationbehind the seats

Competition

SubwoofersNot viable. The source states directly that a big box will not work in this car and neither will anything but the most compact powered sub
Box typen/a
Locationn/a

Door speaker fitment

Sizes and depths below are what research turned up for this generation. Confirm against your own vehicle before cutting or ordering — trim levels vary.

Front doors Likely

Factory speaker sizeNONE FROM THE FACTORY. The source states it plainly: this Corvette did not have door speakers when it left the plant. WHAT IS IN YOUR DOORS DEPENDS ENTIRELY ON WHAT A PREVIOUS OWNER DID — if speakers were added at some point, replacements come in 4", 5-1/2" or 6-1/2", and the source's instruction is to FIGURE OUT WHAT SIZE IS ACTUALLY IN YOUR DOORS BEFORE ORDERING.
Known obstructionsIF YOU WANT DOOR SPEAKERS AND THE CAR DOES NOT HAVE THEM, YOU MUST CUT HOLES IN THE DOORS. The source suggests farming that out to a car audio shop depending on your skills. This is the only vehicle whose door fitment is genuinely unknowable from the model year alone, because the location is entirely aftermarket.
Adapter bracket neededUnknowable — depends on whatever a previous owner installed

Rear doors Likely

Factory speaker sizeNone — two-door car with no rear doors.
Known obstructionsn/a
Adapter bracket neededn/a

Factory audio integration

Factory amp / premium audioNo amplifier, no premium tier — a shaft-style AM/FM/Cassette radio blended into the dash. Nothing to bypass and no impedance trap. The difficulty here is purely mechanical and historical: a dash never designed for a modern receiver, and a car old enough that a previous owner has probably already modified something.
Adding subs without a head-unit swapYes, but only a compact powered sub — the source explicitly rules out anything larger. It also suggests strong-bass rear speakers as an alternative to a sub entirely, on the reasoning that you are sitting very close to them.
Head unitNo replacement needed

Known integration products

Mounting locations

Trunk Likely

NO MEASURED DIMENSIONS, AND AN EXPLICIT CEILING INSTEAD. The source does not hedge: "a big subwoofer box just isn't going to work in this car. Nor will anything other than the most compact powered subwoofer." It also offers a genuinely practical alternative to a sub at all — because you sit so close to every speaker in this car, choosing REAR SPEAKERS WITH SOLID BASS PERFORMANCE may be enough on its own.

Build it for this vehicle

Each link opens the tool with this vehicle already selected.

Before you cut anything

Measure your own vehicle. Trim levels, factory subwoofer options, and mid-generation changes all move these numbers, and a box cut to a researched figure that does not match your truck is wasted wood. Where a badge reads Unconfirmed, treat the value as a starting point for your own measurement, not as an answer.