Will this gasket work with an aftermarket header or just the factory unit?

This gasket is designed for factory exhaust manifolds. If you've swapped to an aftermarket header, verify the bolt spacing and port configuration match before ordering—mounting patterns can differ.

Do I need any fasteners to install this, or are bolts included?

Bolts are not included. You'll use your existing manifold bolts. Have them ready and hand-tighten first, then work your way around evenly to prevent warping the gasket.

Can I reuse the old bolts, or should I get new ones?

Reusing bolts is fine as long as they're not stripped or bent. If any bolt spins freely or looks damaged, replace it before installing the gasket—a loose bolt will cause exhaust leaks.