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: Crew Cab
These are researched envelopes, not a guarantee. Measure your own vehicle — the numbers here tell you what to expect, not what you have.
| Location | underseat storage compartment, crew cab — shares this cavity with the current-gen 1500 (see that page's envelope for full detail) |
|---|---|
| Outer bounding box | ~53"L x 10"W x 10"H (front) / 8"H (rear), same as the 1500 page given confirmed shared underseat geometry. Vehicle-specific enclosure catalogues; published box footprints are lower bounds on the cavity, not the cavity: Kicker 'Chevy/GMC-Specific Dual 12" L7T 2-Ohm Enclosure': 52" W x 7-7/16" H x 15-1/2" D (Kicker's labels; the box is formed to the cab contours), under the back seat. Kicker says 2019-on trucks fit "but not as perfectly" (the box is shaped for the 2008-2018 floor), so its 52"W x 7-7/16"H is narrower and lower than the ~53"L x 10"H figures above — a box that clears the cavity, not the cavity. |
| Known obstructions | None specifically documented beyond the front-to-rear height taper |
| Usable volume estimate | 3 ft³ |
Suggested configurations for this vehicle, not prescriptions. Run the numbers in the Box Builder before you buy anything.
| Subwoofers | 1x10" sealed |
|---|---|
| Box type | sealed |
| Location | under rear seat |
| Subwoofers | 2x10" ported (600-1400W) or 2x12" (1600W) |
|---|---|
| Box type | ported |
| Location | under rear seat, same downfire depth constraints as the 1500 page (5"/7"/+0.55" upfire) likely apply — verify |
Sizes and depths below are what research turned up for this generation. Confirm against your own vehicle before cutting or ordering — trim levels vary.
| Factory speaker size | 6x9" — confirmed via a named Kicker direct-fit kit, matching the current-gen 1500 T1XX page's own confirmed 6x9" spec — evidence the platform unification extends to door speaker size too, not just underseat cavity. |
|---|---|
| Adapter bracket needed | unconfirmed |
| Tweeter | Dash corner |
| Midrange | n/a — see the unresolved tweeter/midrange naming conflict above |
| Factory speaker size | 6.5" (Crew Cab) — Metra's full audio packages for Bose-amplified 2020-2023 and 2024-up 2500HD/3500HD Crew Cab trucks replace the rear door speakers with "VIBE 6.5" Rear Door Speakers" on rear door adapter plate 82-3006; a replacement-kit size, not a GM spec. A genuine OEM speaker set listing describes the factory rear speaker as a coaxial design. |
|---|---|
| Adapter bracket needed | unconfirmed |
| Tweeter | n/a — tweeter/midrange (whichever it is) is a dash-corner, front-only component |
| Factory amp / premium audio | Two-tier finding, continuing the Denali/High Country Bose pattern from the 2014-2019 companion page. Standard Denali/High Country tier: 7-speaker Bose + Richbass woofer (same as the prior generation). A higher tier — GMC's 'Bose Premium Series'/Denali Ultimate naming — steps up to 12 speakers + Richbass woofer + Active Sound Management (engine harmonic cancellation), a real functional addition beyond speaker count, paralleling the same Denali-Ultimate-tier step-up pattern confirmed on the Yukon companion page. Exact model year the higher tier was introduced within 2020-2024 not confirmed. Bose (the system maker, undated pages): Silverado HD "7 high-performance speakers, including a Richbass woofer"; GMC Sierra Denali 7 including a Richbass woofer; Sierra Denali Ultimate and Sierra AT4X 12 speakers including Centerpoint and AudioPilot. Bose's GMC page does not list the Sierra HD itself, so the Sierra HD tiers are inferred from the Sierra pages only. Consistent with the two tiers above. |
|---|---|
| Adding subs without a head-unit swap | Confirmed straightforward — same product ecosystem as the current-gen 1500 |
| Head unit | No replacement needed |
GENUINELY INTERESTING FINDING: the same commercial products (Stinger dual-10", Skar quad-8" and dual-12" 1600W) are sold as fitting BOTH the 1500 (2019+) crew cab AND this HD (2020+) crew cab with identical specs. This means the CURRENT generation unified the 1500 and HD crew cab underseat geometry — unlike the PREVIOUS generation, where the 2014-2019 HD page already has its own distinct spec, separate from the 2014-2018 1500. Don't assume this unification applies retroactively to the older generation.
Outside links. Some are commercial products, some are owner builds posted on forums — the label says which. We do not endorse any of them.
Each link opens the tool with this vehicle already selected.
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.