Dorman 674-425 Exhaust Manifold - Left

Brand Dorman 674-425
Position Left
Material Cast iron
Material Hierro fundido
Color Gris metálico
Color Metallic gray
Port Shape Redondo
Port Shape Round
Collector Port Diameter 3
Oxygen Sensor Port Oui
Oxygen Sensor Port
Oxygen Sensor Port Yes
Tube Wall Thickness 0.125
Mounting Hardware Included No
Mounting Hardware Included Non
Grade Type Reemplazo estándar
Grade Type Standard replacement
Gasket Or Seal Included Oui
Gasket Or Seal Included
Gasket Or Seal Included Yes
Mounting Hole Quantity 8
Heat Shield Included Oui
Heat Shield Included
Heat Shield Included Yes
Contenidos del paquete 1 múltiple
Contenidos del paquete 3 arandelas
Contenidos del paquete 3 juntas
Contenidos del paquete 3 tornillos
Package Contents 1 manifold
Package Contents 3 gaskets
Package Contents 3 screws
Package Contents 3 washers
Fits Chevrolet and GMC · 26 vehicles

Standard replacement. Matches the fit and function of the original manifold.

Cast iron construction. Built for durable exhaust performance.

Includes gaskets and hardware. Supports a complete repair.

Cross-references 12631812 for the same application. See all 1.

$125.60Free shipping
In stock · usually ships same day before 1pm CST
Step 1 — Confirm fitment
Free return shipping if it doesn't fit when you check fitment here first.

Select your vehicle to confirm fitment
Verify this part fits before purchasing — free returns if it doesn't
Step 2 — Quantity
Order total $125.60
Free shipping to the continental U.S.
Free returns within 60 days if it doesn't fit when fitment is verified.

Dorman 674-425 Exhaust Manifold

Dorman 674-425 is a cast iron exhaust manifold engineered to match the fit and function of the original manifold on specified vehicles. It is built for the left side and includes the gaskets and downpipe hardware needed for a complete exhaust manifold repair.

  • Cast iron construction for durability and heat resistance
  • Round port shape with a 3-inch collector port diameter
  • Oxygen sensor port included for direct sensor transfer
  • Heat shield included to match OE-style thermal protection
  • Standard replacement grade for factory-style fit and function
  • Compatible with 2014-2018 Chevrolet Silverado 1500, left
  • Compatible with 2014-2018 GMC Sierra 1500, left
  • Compatible with 2017 Chevrolet Silverado 2500, left
  • Compatible with 2018-2020 Chevrolet Express 2500, left
  • Compatible with 2018-2020 Chevrolet Express 3500, left
  • Compatible with 2018-2020 GMC Savana 2500, left
  • Compatible with 2018-2020 GMC Savana 3500, left

Detailed Product Overview

This exhaust manifold is designed for vehicles that need a direct-fit replacement on the left side of the engine. The cast iron body helps manage exhaust heat, while the OE-style port layout, oxygen sensor provision, and included gasket set support a proper repair on Chevrolet Silverado 1500, GMC Sierra 1500, Chevrolet Express, and GMC Savana applications. Part number 674-425 is a practical choice when replacing a cracked, warped, or leaking manifold on the listed vehicles.

This part cross-references GM OE 12631812 for the same application.

Common Repair Symptoms

  • Exhaust leak noise from the manifold area
  • Visible cracking or warping in the original manifold
  • Burning smell from escaping exhaust gases
  • Check engine light related to exhaust or oxygen sensor readings
  • Loss of exhaust sealing at the cylinder head or downpipe connection

Installation Notes and Tips

Verify left-side fitment before ordering and compare the original manifold, port layout, and oxygen sensor location to the vehicle. Inspect the cylinder head and downpipe sealing surfaces for damage before installation. Replace any worn fasteners or damaged sensors as needed during the repair, and follow the vehicle manufacturer’s torque sequence and specifications.

Quality Assurance

Dorman designs this manifold as a standard replacement part to match original fit and function on the specified applications. Part number 674-425 is manufactured for direct replacement use on the listed Chevrolet and GMC vehicles.

This part fits 26 vehicles
Always verify fitment with your vehicle's VIN if unsure. Submodel & trim restrictions may apply.
YearMakeModelLitersCylindersPositionNotes
2020ChevroletExpress 25004.3LV6Left
2020ChevroletExpress 35004.3LV6Left
2020ChevroletExpress Cargo4.3LV6Left
2020GMCSavana 25004.3LV6Left
2020GMCSavana 35004.3LV6Left
2019ChevroletExpress 25004.3LV6Left
2019ChevroletExpress 35004.3LV6Left
2019ChevroletExpress Cargo4.3LV6Left
2019GMCSavana 25004.3LV6Left
2019GMCSavana 35004.3LV6Left
2018ChevroletExpress 25004.3LV6Left
2018ChevroletExpress 35004.3LV6Left
2018ChevroletExpress Cargo4.3LV6Left
2018ChevroletSilverado 15004.3LV6Left
2018GMCSavana 25004.3LV6Left
2018GMCSavana 35004.3LV6Left
2018GMCSierra 15004.3LV6Left
2017ChevroletSilverado 15004.3LV6Left
2017ChevroletSilverado 25004.3LV6Left
2017GMCSierra 15004.3LV6Left
2016ChevroletSilverado 15004.3LV6Left
2016GMCSierra 15004.3LV6Left
2015ChevroletSilverado 15004.3LV6Left
2015GMCSierra 15004.3LV6Left
2014ChevroletSilverado 15004.3LV6Left
2014GMCSierra 15004.3LV6Left
Directly replaces or cross-references 1 part number
Cross-reference numbers are provided for identification purposes only. Always confirm fitment before ordering.
12631812