Will these plug into my factory wiring harness or do I need a custom harness?

Wiring configuration not specified in the product details. Test-fit the connectors to your vehicle's existing bumper light harness before purchase to confirm compatibility.

Do these require any painting or prep before installation?

The lens comes finished in your selected color — black, smoke, or clear. The hard panel body is ready to install as-is. No additional paint or prep needed.

Are these true LED bulbs I can replace later, or are they a sealed unit?

These are integrated LED assemblies with the optics molded into the unit. They function as a complete light fixture rather than individual bulbs you swap out.