1999-2002 GMC Sierra Extended Cab

1999 • 2000 • 2001 • 2002


John Pollard

John Pollard spent the first six years of his time at Crutchfield on the phone helping people as an Advisor. He later joined the writing staff, focusing on car stereo gear. A native of Charlottesville, VA, he left our rolling hills for the idyllic wonderland of Seattle. Despite the distance, John still works for us, leading up a special project for our vehicle photos database.

More from John Pollard

This article is an overview of your vehicle's audio system and its upgrade options. If you're looking for step-by-step instructions on how to install a car stereo or speakers in your Sierra, there's nothing better than our exclusive Crutchfield MasterSheet™. This detailed, well-illustrated document is free with your Crutchfield order, or you can purchase one separately for $9.99.
GMC Sierra Extended Cap pickup

The GMC Sierra Extended Cap pickup (Crutchfield Research Photo


GMC’s Sierra is a workhorse, and its toughness is evident by the number of older trucks you still see on the road. This truck may get the job done, but the factory stereo comes up a little short. There are plenty of ways to bring it up-to-date with better sound and features like satellite radio and Bluetooth® connectivity.

Factory stereo

You can replace the factory radio with either a single-DIN (2" tall) or double-DIN (4" tall) receiver. (Crutchfield Research Photo)

Replacing the factory radio

Sierras were equipped with GM’s standard AM/FM CD player, which is slightly taller and shallower than most single-DIN aftermarket stereos.

A  vast number of single-DIN (2" tall) and double-DIN (4" tall) stereos will fit right in, with the help of a dash kit that's designed specifically for your truck. You'll also need an antenna adapter and a wiring harness adapter that will allow you to connect the new radio without having to cut into the factory wiring. All of those items are available at a healthy discount with your order, and you'll also get a free Crutchfield MasterSheet, which contains illustrated, step-by-step instructions on how to install a new stereo and speakers in your truck.

This truck offered an analog version of OnStar® which is no longer available, so that won't be an issue when replacing your radio. The column-mounted shifter, however, might be. A receiver with a flip-out screen probably isn’t a good idea in this truck because the screen will hit the gearshift  when it opens.

Aftermarket mounting kit

This mounting kit holds a single-DIN radio. We also have a kit that works with double-DIN receivers.  (Crutchfield Research Photo)

Steering wheel audio controls

Not all Sierras came with steering wheel audio controls, but if yours did, it's relatively easy to keep them. Two companies (PAC and Axxess) make adapters that allow you to connect your Sierra's steering wheel audio controls to a new car stereo. There’s no data wire in this truck, so you’ll tap into the steering wheel controls in the dash. That means either the PAC or Axxess piece will work equally well.

Tools needed: Panel tool 

Shop for car stereos that fit your GMC Sierra 1500

Replacing your factory speakers

Front door speaker

This Sierra front door holds a 6-1/2" speaker with an integrated bracket. (Crutchfield Research Photo)

Front doors 

Stock speakers for the front of the Sierra are 6-1/2", a common size with great aftermarket support. You won’t have trouble finding a speaker to fit any musical taste or budget. You can install a 6-1/2" or 5-1/4" speaker using a simple adapter plate for easy installation, and you can also install the slightly larger 6-3/4" speaker if you’re willing to drill some new screw holes.You’ll need wiring harnesses to connect your new speakers. They'll allow you to attach the new speakers to the plugs that connect to the GM factory speakers, and they make it easier to reinstall the factory speakers if you ever sell your truck Crutchfield gives you a nice discount on mounting brackets and speaker wiring harnesses with every speaker order.

Tweeter in the upgraded system

This tweeter is found mounted above the speaker in the front door if you have the less common 6-speaker system. (Crutchfield Research Photo)

Some Sierra are also equipped with tweeters in the doors. These are also easy to remove, and offer a handy mounting spot should you want to add aftermarket units. You’ll have to fashion a mounting plate for the new tweeter.

Tools neededPanel tool, 7mm socket, wrench, and extension

Rear doors/side panels

Many Chevy and GM vehicles use 4"x6" speakers, and this truck is no exception. There are 4"x6" speakers in the rear doors in the 4-door Sierra Extended Cab, or in the rear door and side panel of the 3-door version. Once you’ve removed the body panels to get to these speakers, they’re extremely easy to take out, thanks to their clip-in plates.

Rear%20door%20speakersRear doors hold 4"x6" speakers. (Crutchfield Research Photo)
Rear%20door%20speakerThe 3-door Extended Cab truck has a 4"x6" speaker in the rear door and in a rear side panel. (Crutchfield Research Photo)

You have plenty of aftermarket options for upgrading these speakers, including 4"x6" plate speakers, as well as 3-1/2" or 4" speakers which will fit using inexpensive adapter plates. You will have to drill new screw holes to accommodate new rear speakers, though.

Tools needed: Panel tool, 7mm socket, wrench, and extension

Shop for speakers that fit your GMC Sierra 1500

JL Audio subwoofer box

These JL Audio Stealthboxes contain 10" subs and fit under each side of the rear bench seat.

Bass in your Sierra

Nothing but good news here. You’ll find an amazing number of subwoofer options for every body style of this popular truck. If you want bass, you should be able to find a nice enclosure that won’t take up too much space in your Sierra.

You'll find that custom enclosures, like the JL Audio Stealthboxes show here, are the best solution for adding bass without giving up valuable interior space.

Custom boxes are built to fit in out-of-the-way places and still let you get the big bass that only 10" or 12" subwoofers can provide.

Other Options

As you might expect with a truck as popular as the Sierra, there are lots of ways to upgrade your entertainment, security, and more.


Like most pickup trucks, the Sierra has a rather noisy cabin. If you really want to hear your music without taxing your speakers, add an amplifier. There are plenty of inexpensive options that will give you the ability to hear your music loud and clear, especially when paired with some upgraded speakers and some Dynamat in your doors. Mounting options abound; but the best bet is under the front or rear seats.


Your truck wasn't available with factory navigation, but you can add an aftermarket double-DIN nav receiver with help from a dash kit. Depending on how you use your truck, a portable navigation unit could also be a good solution, becaue you can move it between vehicles as needed and tuck it into a storage compartment when you're not using it.


You can install a security system in this Sierra without a module. If you’re installing a remote start system in this truck, you will need the PLJX immobilizer override, along with a relay to power up the extra ignition circuit. Also, if you want to control the door locks, you'll need two relays if your alarm or remote start system doesn't support 3 wire positive switching locks.

Upgrading your Sierra

Quick & easy
This truck is easy to upgrade, so go ahead and swap out the front speakers and replace the factory stereo with a stereo that puts out more power – the difference in sound quality will be impressive. Your options for an aftermarket stereo are limited to single-DIN units, so spend a little more on a deck that you can upgrade in the future (preamp outputs, Bluetooth functionality, iPod® adapters, etc.).

More bump in your truck
Once you have a new head unit with preamp outputs, expand your system with some amps and a subwoofer. The custom-made enclosures for this truck are amazing – they tuck out of the way, and some come pre-loaded with some of the best subs on the market. Make sure you feed them enough power to really let them achieve their full potential.

Safety, sound and performance
Head unit, speakers, amps and subs – your truck sounds great, now make it more functional. Adding features like a Bluetooth interface keeps you safe on the road, or install a DVD player to turn the bed of your Sierra into your own private movie theater.

Last updated October 20, 2015
  • brent Billings from Gallipolis

    Posted on 7/23/2015 9:48:04 AM

    Do you know where I can find a exact fit power seat for my 01 gmc 5.3 truck

  • Alexander Hrabe from Crutchfield

    Posted on 7/23/2015 9:57:50 AM

    Brent, best to check with the dealership, or if you're happy with something second-hand, you could try eBay or the good ol' junk yard. Could be a fun adventure!

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