Hex-style replacement valve cover bolts for your 2004.5-2016 (LBZ/LLY/LML/LMM) Duramax truck. The replacement bolts in the ARP 400-7534 kit are much stronger and more reliable than the stock bolts—whether your truck is stock or over 1,000 horsepower, these bolts are a worthwhile upgrade to give you peace of mind.