Contact us
Close contact box
Connect ID #
248 711 13

Our hours

Connect ID #
248 711 13
Chat
All finished with your chat session?

We’ll email you a transcript of this conversation for your records.

For simple questions about your order,
try our new virtual agent:

Please enter your name.  
Please enter a valid email address. Why is this required?
Please enter your US phone number.  

For Tech Support, call 1-888-292-2575

Thank you, !
Our conversation will be emailed to
Please enter a question  
Don't wait on hold. We'll call you back when it's your turn to talk with the next available .
Please enter your name  
Please enter your phone number  

Please enter a message  

Calls may be recorded for training and quality control purposes.

We are located in Virginia USA.

Customer Reviews

Metra 40-GM21 Antenna Adapter

Works with select 1987-up General Motors vehicles — factory male to female Motorola antenna connector

MFR # 40-GM21

Metra 40-GM21 Antenna Adapter

Metra 40-GM21 Antenna Adapter

Works with select 1987-up General Motors vehicles — factory male to female Motorola antenna connector

MFR # 40-GM21

21 reviews
View this product

Antenna Adapter

Crutchfield customer from Peterborough, NH on 1/16/2020

2003 Chevrolet Avalanche

Verified customer (What's this?)
Verified employee purchase (What's this?)

Item fit and worked perfectly. Pleased with my purchase.

Pros: Fit like a dream

Cons: None

Crutchfield response on

0 of 0 found this helpful

Metra 40-GM21 Antenna Adapter

Crutchfield customer from Churchton, MD on 6/18/2019

Verified customer (What's this?)
Verified employee purchase (What's this?)

Good fit. Everything works as it says.

Pros:

Cons:

Crutchfield response on

0 of 0 found this helpful

Metra 40-GM21 Antenna Adapter

Crutchfield customer from Clarksdale, MS on 3/6/2019

2003 Chevrolet Silverado 1500

Verified customer (What's this?)
Verified employee purchase (What's this?)

Exactly what I needed to make the connection from module to my vehicle stock radio for installation of an external audio input.

Pros:

Cons:

Crutchfield response on

0 of 0 found this helpful

Metra 40-GM21 Antenna Adapter

Crutchfield customer from Havre De Grace, MD on 7/10/2018

1998 Pontiac Grand Prix

Verified customer (What's this?)
Verified employee purchase (What's this?)

Works great as all Crutchfield products do.

Pros:

Cons:

Crutchfield response on

0 of 0 found this helpful

Metra 40-GM21 Antenna Adapter

Jason from Walland, TN on 6/30/2018

1988 Dodge B Series

Verified customer (What's this?)
Verified employee purchase (What's this?)

The product was great just wrong application wouldn't work for my radio

Pros:

Cons:

Crutchfield response on

0 of 0 found this helpful

Plug and play

Doug from Knightdale, NC on 7/7/2017

Verified customer (What's this?)
Verified employee purchase (What's this?)

Plug and play it works

Pros: Easy install made rest of installation easier

Cons:

Crutchfield response on

0 of 0 found this helpful

Metra 40-GM21 Antenna Adapter

Jeremy L. from Swansboro, NC on 2/21/2017

2006 Hummer H3

Verified customer (What's this?)
Verified employee purchase (What's this?)

Exact fit. High quality and fast shipping. I have been buying from Crutchfield since I was a teenager and I will continue to buy from them.

Pros:

Cons:

Crutchfield response on

0 of 0 found this helpful

Metra 40-GM21 Antenna Adapter

Richard from Tavernier, FL on 9/25/2016

2003 Chevrolet Blazer

Verified customer (What's this?)
Verified employee purchase (What's this?)

Did not fit..... I ORDERED THE WRONG PART. They refunded the part immediately, no questions asked

Pros: Great customer support and prompt service

Cons: None

Crutchfield response on

0 of 0 found this helpful

Metra 40-GM21 Antenna Adapter

jg from North Carolina on 9/7/2015

Verified customer (What's this?)
Verified employee purchase (What's this?)

cheaply made had to electrical tape together

Pros:

Cons:

Crutchfield response on

1 of 1 found this helpful

Backwards

Crutchfield customer from Indiana on 1/20/2015

1998 Saturn SC1

Verified customer (What's this?)
Verified employee purchase (What's this?)

Did not fit. The connections were backwards.

Pros:

Cons: Did not fit, connections were the opposite of what my GM car required.

Crutchfield response on

1 of 1 found this helpful

perfect fit

jroman from rockford,il on 9/7/2014

Verified customer (What's this?)
Verified employee purchase (What's this?)

perfect fit adds satelite to factory radio using xm module

Pros: keeps factory radio adds satelite with module

Cons: none

Crutchfield response on

2 of 2 found this helpful

worked like a charm

joe from fredericksburg on 2/22/2014

2000 GMC Yukon XL

Verified customer (What's this?)
Verified employee purchase (What's this?)

my only gripe with gm vehicles is their ant. cables.does anybody know the reason for using small cables?

Pros:

Cons:

Crutchfield response on

1 of 1 found this helpful

Simple and easy

AlcoholicProgram from Pittsburgh, PA on 9/1/2013

1997 Cadillac DeVille

Verified customer (What's this?)
Verified employee purchase (What's this?)

Possibly the easiest thing to install so far. The GM Antenna adapter by Metra could not be any better. It does exactly as intended. If the low price scared you, or might even have you jump right into purchasing it, think again. The GM Adapter by Metra is the best product for its use and makes installing a new system that much easier and better.

Pros: Works perfect, simple install, very inexpensive.

Cons: Absolutely none.

Crutchfield response on

1 of 2 found this helpful

Metra 40-GM21 Antenna Adapter

Timi from San Mateo, CA on 8/17/2013

1998 Oldsmobile Cutlass

Verified customer (What's this?)
Verified employee purchase (What's this?)

Good product but couldn't use it because I did not specify which one I needed.

Pros:

Cons:

Crutchfield response on

0 of 0 found this helpful

Just the ticket too

Hap from MT on 7/4/2013

Verified customer (What's this?)
Verified employee purchase (What's this?)

This fits the radio and lets a regular antenna work on GM products.

Pros:

Cons:

Crutchfield response on

1 of 1 found this helpful

Too long

Ken from Saint Paul, MN on 5/19/2013

2001 Chevrolet Tahoe

Verified customer (What's this?)
Verified employee purchase (What's this?)

Worked like a charm

Pros: Plugged in tight.

Cons: Too long. Had issues with stuffing it an all the other wires back. behind stereo.

Crutchfield response on

0 of 0 found this helpful

Great Adapter

C P from Tuscaloosa, Al on 5/6/2013

Verified customer (What's this?)
Verified employee purchase (What's this?)

Great adapter, had no problems installing in my 2002 Chevy S-10.

Pros: Great adapter, easy installation

Cons: None

Crutchfield response on

1 of 2 found this helpful

Metra 40-GM21 Antenna Adapter

John W. from Cuba, NY on 3/26/2013

Verified customer (What's this?)
Verified employee purchase (What's this?)

Easily attached to my FM modulator.

Pros:

Cons:

Crutchfield response on

0 of 0 found this helpful

Worked great

TSub from Central KY on 1/29/2013

Verified customer (What's this?)
Verified employee purchase (What's this?)

This worked great for taking my Suburban back to a stock radio. The adapter made it easy to put a factory style radio back in since the antennas are somehow different. Had no issues with loose connections either.

Pros:

Cons:

Crutchfield response on

1 of 1 found this helpful

Don't Know Yet

Billy M from Sumrall, Mississippi on 1/2/2013

2006 Pontiac Grand Prix

Verified customer (What's this?)
Verified employee purchase (What's this?)

Had to use this with an adaptor for FM modulator of iPod. Did not fit very tight on a GM radio. Still works, but it seems like if ever hit a large bump in the road it's probably going to come out. But I may be wrong.

Pros: Works, so far.

Cons: Fits loosely in GM radio.

Crutchfield response on

0 of 0 found this helpful

Metra 40-GM21 Antenna Adapter

Michael from Flagstaff AZ on 2/21/2009

2004 Chevrolet Malibu (Classic)

Verified customer (What's this?)
Verified employee purchase (What's this?)

Why does GM use a weird miniturized Motorola antenna connector? Dunno, but they do. This is the answer (or if you are installing an XM modulator in-line, it is half the answer.)

Pros:

Cons:

Crutchfield response on

7 of 9 found this helpful

TOP