Will this bolt directly onto my vehicle without modification?

Yes. This unit mounts at factory attachment points with no drilling or panel cutting required. Test-fit before final installation to confirm alignment.

Do I need to splice this into the factory wiring harness?

The assembly comes ready to install, but wiring connection method is not specified in the product data. Check your vehicle's service manual or consult a technician for proper harness integration.

What's the difference between this and the amber OEM marker?

This is white LED instead of amber halogen. You get better visibility, longer bulb life from the LED, and a cleaner aesthetic. The white output is sharper and brighter in low-light conditions.