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Metra 40-GM21 Antenna Adapter

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

for matching vehicles with all car stereos $119+ for matching vehicles with all car stereos $119+
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  • Metra 40-GM21 Antenna Adapter

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Metra 40-GM21 adapter

The Metra 40-GM21 adapter lets you connect an aftermarket antenna cable to the factory radio. It has a female Motorola plug on one end and a right angled male GM antenna plug on the other. This adapter can also be used when installing a wired FM modulator with the factory radio. Please enter your vehicle information or call an Advisor at 1-888-955-6000 to find out if this adapter is compatible with your vehicle. Warranty: 60 days.

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Note: Most vehicles will require additional installation parts — please identify your vehicle if you haven’t done so, then check here for a list of parts. You can also call an Advisor for more information.

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What's in the box?

Download owner's manual

  • 6.438" antenna adapter cable (one end terminating in a female Motorola plug and the other end terminating in a right angled male GM antenna plug).

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Features

Compatibility: 1987 and later GM factory radio with mini connector to universal antenna adapter cable (factory radio to universal antenna)

 
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Metra 40-GM21 Antenna Adapter Reviews

Average Customer Review:

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5 out of 5

worked like a charm

Written By joe, fredericksburg on Saturday, February 22, 2014
Crutchfield Customer Review (What's this?)
 
my only gripe with gm vehicles is their ant. cables.does anybody know the reason for using small cables?
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5 out of 5

Simple and easy

Written By AlcoholicProgram, Pittsburgh, PA on Sunday, September 01, 2013
Crutchfield Customer Review (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.
1 out of 1 people found this helpful
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4 out of 5

Metra 40-GM21 Antenna Adapter

Written By Timi, San Mateo, CA on Saturday, August 17, 2013
Crutchfield Customer Review (What's this?)
 
Good product but couldn't use it because I did not specify which one I needed.
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5 out of 5

Just the ticket too

Written By Hap, MT on Thursday, July 04, 2013
Crutchfield Customer Review (What's this?)
 
This fits the radio and lets a regular antenna work on GM products.
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4 out of 5

Too long

Written By Ken, Saint Paul, MN on Sunday, May 19, 2013
Crutchfield Customer Review (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.
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5 out of 5

Great Adapter

Written By C P, Tuscaloosa, Al on Monday, May 06, 2013
Crutchfield Customer Review (What's this?)
 
Great adapter, had no problems installing in my 2002 Chevy S-10.
Pros:
Great adapter, easy installation
Cons:
None
1 out of 1 people found this helpful
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5 out of 5

Metra 40-GM21 Antenna Adapter

Written By John W., Cuba, NY on Tuesday, March 26, 2013
Crutchfield Customer Review (What's this?)
 
Easily attached to my FM modulator.
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5 out of 5

Worked great

Written By TSub, Central KY on Tuesday, January 29, 2013
 
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.
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3 out of 5

Don't Know Yet

Written By Billy M, Sumrall, Mississippi on Wednesday, January 02, 2013
Crutchfield Customer Review (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.
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5 out of 5

Metra 40-GM21 Antenna Adapter

Written By Michael, Flagstaff AZ on Saturday, February 21, 2009
Crutchfield Customer Review (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.)
6 out of 7 people found this helpful
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