| Country of Origin | United States |
|---|---|
| Brand | GM |
| To Control | transmission |
| Type | Switch Assembly |
| OE/OEM Part Number | Littlefuse Little Fuse 1971, 3990843 |
| Color | Silver |
| Manufacturer Part Number | 3990842, 3990843 |
| Features | Durable |
| Vintage Part | Yes |
| Universal Fitment | No |
| Placement on Vehicle | Front |
| Performance Part | No |
Check the listing for details. OEM GM TSC Reversing Relay 3990842 3990842 1971 Corvette Camaro Chevelle Smog. Color: Silver, Condition: Used, Made in United States. Listed at 69.00 USD. GM Transmission Spark Control (TSC) reversing relay, part number 3990842, and TSC, delay spark relay 3990843. Fits 1971 Chevrolet Corvette, Camaro, Chevelle, and similar models equipped with factory smog/AIR systems. Great for emissions restoration of 1971 GM vehicles. 80 Amp Relays. These are usually located on the gutter wire harness on the firewall. No box. Both tested and work great.