Do these mount at factory rocker points, or do I need to drill?

These mount at factory attachment points—no drilling needed. Line them up with your existing mirror location and bolt through.

Will these mirrors vibrate or rattle at highway speeds?

Manual mirrors are solid mechanical units with no motors to bind up or electronic linkages to fail. Tighten the bolts and adjustment locks down properly, and vibration is minimal. If you hear rattle, check that all fasteners are snug.

Do the LED signals come wired, or do I need to splice them into my truck's harness?

Wiring diagram and harness integration method are not specified in the product data. Contact support with your truck's year to confirm the signal wire routing and whether adapter harnesses are available separately.