MTX ThunderForm Unloaded Enclosure

Holds two 10" subs — fits select 2001-06 Chevrolet Silverado or 2004-06 GMC Sierra Crew Cab (Heavy Duty) (Charcoal)

  • MTX ThunderForm Unloaded Enclosure

    Charcoal (subs not included)

  • MTX ThunderForm Unloaded Enclosure

  • MTX ThunderForm Unloaded Enclosure

  • MTX ThunderForm Unloaded Enclosure


Our take on the MTX ThunderForm Unloaded Enclosure

by Jo Greene

Crinkled french fries, discarded receipts, old gum wrappers — you probably have everything in the hidden corners of your vehicle except great bass. ThunderForm enclosures fill the nooks and crannies of your vehicle with low tones that stand out, but their factory look blends right in.

MTX engineers evaluate the "sonic signatures" of top-selling vehicles so they can design ThunderForms as custom acoustic matches. Each ThunderForm fits and blends inconspicuously into your vehicle, so you get great bass without losing any space. They're made of high-density polyethylene resin to curb resonances — they deliver bass that's tight, hard-hitting, and way down low. The airtight enclosure provides the correct internal volume to yield optimum bass response.

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This enclosure comes without speakers — you install two of your favorite 10" subwoofer. For best results, MTX strongly recommends using a speaker designed for an enclosure with a volume of 0.75 cubic foot. The enclosure mounts behind the rear seat of select 2001-06 Chevrolet Silverado 2500/3500HD or 2004-06 GMC Sierra Crew Cab pickups. The jack stays in the factory location.

Please check with us before purchasing by using the vehicle selector on our site, or calling an Advisor at 1-888-955-6000 to verify fit information.


  • custom-fit charcoal subwoofer enclosure for two 10" subs
  • mounts behind rear seat
  • fiberglass construction
  • volume: 1.5 cubic feet (0.75 per sub)
  • dimensions: 10-3/4"H x 48"W x 6-1/4"BD x 6"TD
  • mounting depth: 5"
  • warranty: 5 years (free repair or replacement for 2 years, prorated replacement for years 3 through 5)
  • Our 60-day money-back guarantee

Hands-on research from the Crutchfield Labs (what are the Labs?)

Features and Specs
Box Type Sealed
Number of Boxes 1
Number of Speakers Per Box 2
Speaker Size 10
Cutout Diameter or Length (inches) 9 3/16
Maximum Speaker Depth (inches) 4-15/16
Box Volume (cubic feet) 1.64
Tuning Frequency N/A
Height (inches) 10-3/4
Width (inches) 48
Depth (inches) 6-1/4
Second Depth (inches) 6
Wood Thickness (inches) 0
Speaker Wire Connectors Spring posts
Box Color Charcoal
Box Finish Fiberglass
Parts Warranty 5 Years (3-5 Prorated)
Labor Warranty 5 Years (3-5 Prorated)
Product Research
What's in the box?

Download owner's manual

  • Custom-fit unloaded dual 10" subwoofer enclosure
  • Hardware
  • Installation instructions

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team — they open the box, verify contents, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.



Mounting Location: The enclosure mounts behind rear seats, firing forward, in 2000-2006 Chevy 2500/3500 HD Crew Cab Trucks (jack stays in factory location).

Note: Please refer to the Crutchfield Vehicle Selector to confirm fit for your vehicle.

Enclosure Type: The sealed enclosure features fiberglass construction and fits two 10" woofers.

Note: Factory colors include - Tan, Charcoal, and Grey.

Tools For Installation:

  • Powered screwdriver
  • #2 Phillips head bit
  • 6" Bit holder extension


5 Year Warranty Terms: This product carries a 5-Year Prorated Warranty with the following terms:

  • Years 1-2: Products found to be defective in materials or workmanship during the first two years will be, at Mitek's option, repaired or replaced by Mitek at no charge. The warranty period does not renew, but continues on from the original date of purchase.
  • Years 3-5: The purchase price of an item which becomes defective after the first two years and prior to the end of the warranty period will be prorated and credited toward the purchase of a new MTX product. The amount of proration is determined by dividing the original purchase price by the number of months in the warranty period (60), then multiplying the result by the number of months remaining in the warranty period.
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MTX ThunderForm Unloaded Enclosure Reviews

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4 out of 5

plug and play boom boom box

Written By Charlie, Dinwiddie VA on Wednesday, February 01, 2012
Crutchfield Customer Review (What's this?)
The box fit perfect, the color match like it was factory. I didn't expect it to be prewired and insulated, that was a nice surprise! The straps they sent with it to put around the fresh air vents were not very useful. They were basically impossible to install. I had some good old reliable 3M velcro. I put two strips along the top and it worked great. I stored the straps for another project later.
Fit perfect, color match made it look factory, prewired and insulated ready to go.
mounting and price
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Don't skimp on the wire you will need to run from your new subwoofer enclosure to your amplifier. See all categories & accessories

T-Spec 16-gauge Speaker Wire Black/white jacket — priced per foot
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For a more in-depth review and enhanced detailed information on the MTX ThunderForm Unloaded Enclosure, please visit the Crutchfield website product page (/ISEO-rccbcspd/p_23625HC20U/MTX-ThunderForm-Unloaded-Enclosure-Charcoal.html ).