Will these mount at the factory mirror locations?

Yes. These bolt to factory mounting points — no drilling or bracket fabrication needed. Test-fit before final tightening to ensure glass clearance with your door panels.

Do the LED markers require separate wiring?

The markers are integrated into the assembly. Run marker power to your truck's side light circuit or check your service manual for the exact connection point on your model year.

How stable are these at highway speeds?

Manual mirrors are inherently rigid once adjusted. Lock your desired position and leave them. If vibration occurs after install, verify all fasteners are tight at the mounting bracket.