Do I need new head bolts after head-gasket work on a 6.0L?

Yes. GM Gen III and IV engines use torque-to-yield head bolts, and Speedway says those belong in the trash once they've been torqued. They're one-use.

Your options:

• New factory-style bolts.
• Upgraded aftermarket head bolts — a good budget choice for mild engines.
• Head studs — better for serious power or boost. Studs pull in a straight line when torqued, so clamping is more accurate and the block threads aren't twisted.

Also scrap any bolt or stud that rusted from a leaking head gasket or has damaged threads.