Do these use factory mounting holes, or do I need to drill?

These mount at factory rocker points — no drilling required. Bolt-on installation using your truck's existing attachment locations.

Will the heated glass stay stable at highway speeds?

Yes. The glass is integrated into a rigid powered assembly designed for towing loads and sustained speed. Heating does not affect structural stability or mirror angle hold.

What about the power and heating connections — are they pre-wired?

The mirror assemblies include wiring pigtails for power and ground. You'll need to route them to your existing power source; splice into factory mirror harness or run dedicated circuits depending on your setup.