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Like most full-size crew cabs, the Silverado and its GMC Sierra twin have a useful space under the rear seat. Lift the cushion and a box shaped for the floor slides in, hidden and out of the way. Which box fits depends on the generation, because makers shape their boxes separately for the trucks before and after the 2019 redesign. Here’s what fits each Silverado and Sierra Crew Cab, and what you’ll need to power it.
The short version
- 2008–2018 1500 (and HD to 2020): Kicker 51KGMDL7T122, dual L7T 12s, 1,200 W RMS at 2 Ω.
- 2019–2025 1500: Skar Audio loaded dual 12, down-firing, pre-wired to 1 Ω.
- 2019 and newer, single sub: Metra’s GM-SL1-10 OEM-style box (sold through dealers).
- No amp? A compact powered sub like the Kicker Hideaway HS10.
- Factory Bose system? Tap the factory amp’s outputs with a converter rated for amplified signals.
Which box fits your truck?
| Truck | Years | Under-seat options |
|---|---|---|
| Silverado / Sierra 1500 Crew Cab | 2008–2018 | Kicker 51KGMDL7T122 |
| Silverado / Sierra HD Crew Cab | 2008–2020 | Kicker 51KGMDL7T122 |
| Silverado / Sierra 1500 Crew Cab | 2019–2025 | Skar loaded dual 12; Metra GM-SL1-10 (to 2026); Skar quad 8 |
Our picks
Kicker 51KGMDL7T122 GM L7T enclosure
For 2008–2018 1500 LD and 2008–2020 HD Crew Cabs.
- Dual 12″ L7T square subs, down-firing
- 2 Ω single terminal
- Handles 1,200 W RMS
- 25–100 Hz
- 52 × 7-7/16 × 15-1/2 in
Kicker’s box sits under the back seat and fires into the floor. At 7-7/16 inches tall it’s shallow for a pair of 12s. Pair it with a mono amp making about 1,200 W at 2 Ω, like the Kicker CXA1200.1. Kicker notes that storage compartments, inverters, tools or floor mats may need removing.
- Two 12s in a very shallow box
- Covers LD and HD trucks
- Kicker build
- Not for 2019+ 1500 trucks
- Needs a strong amp and 4 AWG or larger wiring
Skar Audio loaded dual 12 (2019–2025 Crew Cab)
For the current-generation Silverado and Sierra 1500.
- 2 × Skar VD-12 D4 12″ subs
- Pre-wired to 1 Ω
- Ported, down-firing
- Under the rear seat
Skar shapes this ported box for the newer cab floor. It’s pre-wired to 1 Ω, so pick a 1 Ω-stable mono amp sized to the subs’ RMS rating rather than the max power figure. Our amps for two 12s guide helps.
- Fits the 2019+ cab
- Two 12s, ported
- Sold by Skar Audio
- Needs a 1 Ω-stable amp
Skar Audio loaded quad 8 (2019–2025 Crew Cab)
For tight, punchy bass from four smaller subs.
- 4 × Skar SVR-8 D2 8″ subs
- Pre-wired to 1 Ω
- Ported, front-firing
Four 8s give a lot of cone area with quick response. Check Skar’s fitment notes for exact placement in your cab before ordering.
- Lots of cone area
- Fits the 2019+ cab
- Needs a 1 Ω-stable amp
- Check placement details for your trim
Kicker Hideaway HS10
For any Silverado or Sierra, if you want a simple install.
- Powered 10″ with built-in amp
- Retailers list 180 W RMS
- Remote level, phase, +6 dB boost
A compact all-in-one sub that can sit under or behind a seat. Far less output than the vehicle-specific boxes, but no separate amp or box to fit. See also our JBL BassPro SL2 review.
- No separate amp
- Works with factory radios
- Much less output
Coming soon: Kicker for 2019+ trucks
At SEMA 2026 Kicker showed the 51KGM2DL7T, a dual 12-inch L7T system rated at 1,200 W RMS for 2019–2027 Silverado and Sierra Crew Cabs. Prices and dates aren’t out yet; see our Kicker SEMA 2026 report. We’ll add it here once it’s on sale.
A single-sub OEM-style option
Metra’s GM-SL1-10 is an OEM-fit enclosure for 2019–2026 Silverado and Sierra Crew Cabs. Metra lists it with a 10-inch VIBE BLACKAIR10D2S-V3 sub (dual 2 Ω, 300 W RMS) in a down-firing ported box with 1.8 cu ft of air space, tuned to 36 Hz, measuring 11 × 27 × 15 inches. Pricing is through Metra dealers, so it isn’t linked here.
Factory radio and wiring
- Signal: use a line output converter or an amp with speaker-level inputs. Trucks with a factory Bose system have a separate factory amp; see our premium factory audio guide and converter picks.
- Power: 4 AWG copper for 1,000–1,200 W, 1/0 above that. Our wire gauge calculator helps.
- Electrical: for big systems, the Big 3 upgrade keeps voltage up.
Safety first: disconnect the battery’s negative terminal before you start, fuse the power wire within 18 inches of the battery, and use a professional installer if you’re not comfortable working on your car’s electrics.
FAQs
Will a 2014–2018 box fit a 2019 truck?
Generally not. Makers list these boxes by generation, and the cab was redesigned for 2019, so buy one listed for your exact years.
Does the Kicker box fit Double Cab trucks?
Kicker lists it for Crew Cabs only.
Can I keep the rear-seat storage?
Under-seat boxes usually replace any factory underseat storage. Check the maker’s fit notes.
Sealed or ported for a truck?
Both work. Our sealed vs ported guide covers the trade-offs.