Product Description
Genuine GM 3990842 Transmission Controlled Spark Reversing Relay (NOS)
This genuine GM 3990842 Transmission Controlled Spark (TCS) Reversing Relay is a New Old Stock (NOS) component designed for 1971 Chevrolet Corvette, Camaro, and Chevelle models. Manufactured in the USA, this critical relay manages the TCS emissions system, ensuring proper spark timing control based on transmission gear, a key function for maintaining original emission standards and engine performance.
Key Features:
- Brand: GM
- Part Number: 3990842
- OEM Number: 3990842
- Position: Transmission Controlled Spark (TCS) Emissions System
- Origin: USA
- Condition: NOS (New Old Stock)
Fitment:
| Make | Model | Year | Engine | Notes |
|---|---|---|---|---|
| Chevrolet | Corvette / Camaro / Chevelle | 1971 | Equipped with TCS emissions system |
Fits Years:
1971
Note on Stock Photos: Due to our inventory of multiple identical units for this specific part number, we utilize representative stock photos for this listing. You will receive a component that strictly meets all listed specifications and fitment requirements. Please be aware that because these are vintage parts, minor cosmetic variations—such as surface finish, color, or production markings—may exist between different manufacturing runs. These slight aesthetic differences are a result of historical production processes and do not impact the part's integrity, performance, or authenticity.
A Note on Fitment Accuracy: We manually research our fitment data using vintage manufacturer catalogs to provide you with the most accurate information possible. However, because we are human and these decades-old resources can occasionally contain errors, we cannot guarantee 100% accuracy. We strongly encourage you to perform your own due diligence and verify this part number for your specific application before purchasing. Please note that this part may also fit other vehicles or years not explicitly listed in our research.
Unbeatable Prices & Expectations
While many of our vintage parts were manufactured decades ago, they remain unused and high-quality. Some original boxes may show signs of shelf-wear, such as dust, tape, or surface distress from years of storage. Rest assured, the components inside have been inspected to ensure they are complete and ready to help you finish your project without breaking the bank.
