JL Audio Stealthbox SB-GM-SLVEXT-12W3v2-BU User Manual

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Fits 1999-UPExtended-Cab

Full-SizeGM Pickup Trucks

Installation Guide:

This Stealthbox is a product which requires professional installation skills and tools. Please read this installation guide thoroughly before beginning the project. It will guide you step by step through the installation. Several of the steps in this process may require two people to accomplish.

It is absolutely vital that the enclosure be properly mounted to the vehicle according to these instructions. Failure to mount the enclosure properly presents two problems: 1) The sub-bassperformance will suffer due to the movement of the enclosure caused by the force exerted by the woofer and 2) A loose enclosure presents a serious safety hazard in the event of a collision or sudden deceleration.

STEP 1: Fold the rear bench seat up.

STEP 2: Run speaker wires to the rear of the cab under the bench seat.

STEP 3: Peel the backing from the supplied square of wax and place it on the floor of the cabin in the location shown in the picture. This will be used to mark the location of the hole for the mounting bolt. The wax square should be in the location of the threaded insert in the enclosure when the enclosure is placed in the proper location within the vehicle.

STEP 4: Thread the bolt into the threaded insert in the

Stealthbox. Tighten Fully.

STEP 5: Place the Stealthbox in its mounting location on the floor of the cab. Press down on the enclosure firmly to make an impression on the wax sheet with the head of the mounting bolt.

STEP 6: Remove the enclosure. There should be a clear mark where the bolt pressed into the wax square.

STEP 7: Check under the truck for any loose brake lines, fuel lines or other hazards before drilling.

CAUTION: Always wear eye protection when


STEP 8: Drill a 1/2" diameter hole through the floor pan of the truck using the indentation in the wax square as a guide. Make sure you hold the drill straight and that the hole you are drilling is centered on the wax mark.

STEP 9: Trim speaker wire to length and connect to the enclosure's barrier strip observing correct polarity. Positive is designated by the red wire on the barrier strip.

SB-GM-TRKEXT99/12W3-D2,JL AUDIO, Inc 1999 • Page 1

Sheet SKU#011140 Revision 10/5/01

STEP 10: Place the Stealthbox into its mounting location, tucking the excess wire neatly out of sight. Turn on the system and test the enclosure's operation before bolting it down.

STEP 11: While one person holds the Stealthbox in place inside the truck, bolt the enclosure into place from underneath the truck, using the supplied hardware. Before tightening the bolt, apply a bead of silicone sealant between the flat washer and the vehicle's floor pan. Then tighten the enclosure fully. See diagram below:

Threaded Insert

Enclosure Wall (fiberglass) Molded into


Flat Washer

Vehicle's Sheet Me

Lock Washer

Bead of Silicone Sealant


3/8" Bolt



Once the bolts are tightened, spray undercoating onto the bolt heads to prevent rust, leaks and loosening of the bolts over time. Failure to do so may result in severe corrosion and may present a serious safety hazard.

This completes the installation.


Enclosure Type: Acoustic Suspension (Sealed)

Driver Type: JL AUDIO 12W3-D2Subwoofer

Cont. Power Handling: 250 Watts

Nominal Impedance: 4Ω

Supplied Hardware:

(1) 4" sheet wax square

(1) 3/8" x 1.25" Bolt

(1) Flat washer

(1) Split lock washer

Completed Installation

10369 N. Commerce Pkwy, Miramar, Florida 33025-3921Voice: (954)443-1100Fax: (954)443-1111

SB-GM-TRKEXT99/12W3-D2,JL AUDIO, Inc 1999 • Page 2

Sheet SKU#011140 Revision 10/5/01