The GM 12637647 Replacement Driver Side Exhaust Manifold is a genuine GM replacement for the cracked or leaking manifold in your 2001-2016 GM 6.6L Duramax. A leaking exhaust manifold will cause a loss of power by not letting the turbo spool to its complete potential. This manifold will restore the spool-up, and throttle response, and restore power that was lost due to the leak. This GM OE part is constructed to the same high-quality standards as your factory exhaust manifold. Gasket not included.

• Direct-Fit Replacement
• Genuine GM OE Exhaust Manifold
• Constructed With High-Quality Materials