The 558-486 is Holley's factory service harness for 6.86" and 12.3" M8 Pro Dash displays, giving you a direct replacement connection using the same single M8 connector as the original harness.
Specifications:
- Product Type: Gauge Wiring Harness
- Compatible Dashes: 6.86" and 12.3" M8 Pro Dash
- Connectors: (1) M8 connector
- Finish: Black
- Part Number: 558-486
Verify which M8 dash version you have before ordering, since connector revisions can differ between dash generations.
FAQ
What does the 558-486 harness fit?
It's a service replacement harness for Holley's 6.86" and 12.3" M8 Pro Dash products.
How many connectors are included?
One M8 connector, matching the factory harness configuration.
Should I check anything before I order this harness?
Yes — confirm your M8 dash version before ordering, as connector revisions can vary.

