Do these mount at the factory locations or do I need to drill new holes?

These mount at factory attachment points — no drilling required. They're direct replacements that bolt into the existing mounting positions.

Do I need to remove the door panels to install these?

Yes. Door panel removal is standard for window motor and regulator replacement. You'll need basic hand tools and patience to access the regulator mechanism inside the door cavity.

What happens if one side fails after I install both — can I return just one?

Contact support before installation if you have concerns about individual replacement. Once installed, the full set is considered a unit, so plan your return within the standard window if needed.