Dorman 674-738 Exhaust Manifold - Left or Right

Dorman 674-738 Exhaust Manifold

Dorman 674-738 is a cast iron exhaust manifold engineered to match the fit and function of the original part on specified vehicles. It includes the gaskets and downpipe hardware needed for a complete exhaust manifold repair on select Chevrolet P30 and GMC P3500 applications.

Key Features

• Cast iron construction for durable exhaust service
• Natural finish with a square port shape
• Includes gasket and seal components for the repair
• Mounting hardware included for installation
• Direct-fit replacement for left or right side applications
• Fits 1998-1999 Chevrolet P30, left and right
• Fits 1998-1999 GMC P3500, left and right

Detailed Description

This exhaust manifold is built for 1998-1999 Chevrolet P30 and 1998-1999 GMC P3500 vehicles in left or right position applications. Dorman 674-738 is manufactured to replicate the original manifold’s fit and function, helping restore proper exhaust routing and sealing at the cylinder head and downpipe connection. The cast iron body supports long-term exhaust heat exposure, while the included manifold gasket, flange, studs, and nuts help complete the repair. This part cross-references OE number 12562999 for the same application.

Common Repair Issues

• Exhaust leaks at the manifold-to-head sealing surface
• Cracked or warped original manifold casting
• Broken or missing manifold studs and nuts
• Noise from a leaking exhaust manifold connection
• Failed flange sealing at the downpipe joint

Installation Notes and Tips

Verify engine-side and downpipe alignment before tightening fasteners. Clean the mounting surfaces thoroughly to promote a proper seal, and replace any damaged hardware or mating components during installation. Confirm left or right position fitment for your Chevrolet P30 or GMC P3500 before ordering.

Quality Assurance

Dorman designs this manifold as a direct replacement for specified vehicles, with materials and dimensions selected to match original fit and function. The included gasket and hardware support a complete exhaust repair on the listed applications.