Do these need gaskets or sealant to install?

You'll need header gaskets rated for the 8.0L V10. Check your engine's service manual for the OEM gasket spec — don't skip this step, as a leaking header burns fuel and kills efficiency.

Can I bolt these straight to factory ports?

Yes. These mount at factory rocker points with no drilling or welding. You're swapping headers, not modifying the engine bay.

Will the stainless finish stay polished after installation?

Stainless resists rust and discoloration under normal heat, but the polished look will darken over time as the headers cycle through temperature. A high-temp ceramic coating can preserve the appearance if that matters to you.