Will these bolt straight into my C10 without modification?

These mount at factory headlight points — no drilling or bracket fabrication needed. Test-fit before sealing to confirm alignment with your specific truck's body condition.

Do I need to buy bulbs separately?

Yes. These housings accept standard 9005 and 9006 bulbs, which are sold separately. Your local auto parts store carries them.

Can I paint or polish the black housings?

The black finish is as-shipped. If you want to customize the color, standard automotive paint and primer work on the hard panel material — prep and test on a small area first.