Will these bolt directly to my truck without drilling?

Yes. These mount at factory rocker points — no drilling or frame modification needed. Bolt directly to existing holes on the C/K body.

How do I adjust the mirrors?

Manual adjustment means you turn the mirror head by hand to aim it where you need it. Tighten the bolt once you have the angle locked in. Simple, no moving parts to fail.

Will these mirrors stay stable at highway speeds?

Manual mirrors are solid once tightened. They don't vibrate or drift like motorized units can. Confirm your bolt torque is snug before heading out, and you're good.