Do these plug directly into the factory wiring harness?

These are hard-wired units, so installation involves connecting to your vehicle's rear light harness. Test-fit first to confirm connection points match your specific model before finalizing any splices or modifications.

Will these fit the stock housing or do I need a new panel?

Mounting method and housing compatibility not specified — inspect your current tail light assembly before ordering. Bring dimensions or take photos to confirm fitment with the four-piece configuration.

What's the return window if these don't work?

Contact ModSupply directly with your order number and issue details. Since these are brand new and hard-wired, returns depend on condition upon receipt and your proof of purchase.