Replace the old, cracked, or damaged exhaust manifold on your 2001-2004 Chevy/GMC 6.6L LB7 Duramax and get your engine running right. Durable, high-silicon ductile iron manifolds are offered as an upgrade or stock replacement for many applications. Exhaust manifolds can fail due to cracks or leaks from heat cycles, age, and other extreme conditions. These leaks can reduce power, and also hurt engine efficiency. You'll find top-notch brands such as AFE, BD-Power, ATS, Dorman, and more.