Metra 40-GM21 General Motors Reverse Antenna Adapter 1988-2013

The Metra 40-GM21 Antenna Adapter is designed for select General Motors vehicles. It provides the antenna connection needed when using an aftermarket antenna with the original factory radio.

Key Features

• Vehicle-specific antenna adapter for select General Motors vehicles
• Supports using an aftermarket antenna with the original factory radio
• Female Motorola connector to male GM antenna connector
• Helps maintain the AM/FM antenna connection during radio, antenna, navigation, or FM-modulator integration
• Designed to avoid cutting factory antenna wiring when matched to the correct vehicle and radio configuration

System / Fitment Notes

• Reverse antenna adapter for retaining the factory radio while adapting an aftermarket antenna connection

Vehicle Compatibility

Installation Notes

• Confirm exact year, make, model, factory radio, antenna connector style, and radio being installed before installation
• Test-fit the antenna adapter and review manufacturer instructions before final assembly
• Additional dash kits, wiring harnesses, steering wheel control interfaces, or factory feature-retention parts may be required
• Professional installation is recommended for best results

What’s in the Box

• Antenna adapter cable

Technical Specifications

• Brand: Metra
• Model: 40-GM21
• Product Type: Antenna adapter
• Application: Vehicle antenna integration
• Connector Type: Female Motorola connector to male GM antenna connector

Identifiers & Packaging

• MPN: 40-GM21
• UPC: 86429007073
• Sold As: Each
• Included Components: Antenna adapter cable

Why Buy From MCOR Automotive

• Authorized retailer for the brands we sell
• Specialists in vehicle audio integration, radio replacement parts, and installation accessories
• 22+ years of professional automotive electronics experience
• Expert support for compatibility verification and proper setup