Left Exhaust Manifold Kit

Quality Guaranteed • Aftermarket Value • Backed by Warranty • 30 Day Return Policy

Dorman# 674-506

Replaces General Motors# 3969923

Left Side

Fits the Following Applications:

Automotive Color / Finish: Unfinished
Automotive Item Type: Standard Replacement
Bolt Hole Quantity: 7
Engine Manufacturer: GM
Exhaust Manifold Compatibility: Not Applicable
Exhaust Manifold Inlet Port Shape: Square
Gasket or Seal Included: 1 Flange
Hardware Included: 3 Studs, 3 Nuts, 3 Washers, 3 Lock Washers
Material: Cast Iron
Package Contents: Exhaust Manifold, 1 Flange, 3 Studs, 3 Nuts, 3 Washers, 3 Lock Washers
Notes: Includes Gaskets and Hardware (where required); Left. Corvette Big Block 1974-70, 396,427& 454 CID with 2-1/2" Dia Pipe (LH)

Dorman Exhaust Manifold

More like a complete kit than a single part, many of our Exhaust Manifolds include gaskets and hardware for a complete installation. Since this part is a direct replacement, the exact fit adds another layer of efficiency and convenience.

  • Includes heat-shield for protection of hoses, wiring, and other engine components
  • Cast iron or stainless tubular construction protects against warping and/or cracking
  • Leak-resistant for long-lasting performance
  • A rigorous quality inspection has been undertaken to ensure that this part conforms to product standards
Search Keywords: Exhaust, Manifold, Manifolds
Alternate Names: Exhaust Header
Dorman Exhaust Manifolds

Exhaust Manifold
Frequently Asked Questions

What is an Exhaust Manifold?
  • Exhaust manifolds do many different jobs (depending on application):
    • Transporting extremely hot exhaust gases (up to 1400 F) from the cylinder head to the exhaust piping.
    • Providing mounting for Oxygen sensors, A.I.R. piping, and EGR piping.
    • Sealing the engine head and exhaust piping to prevent fumes and noise from escaping the engine compartment.
Why do Exhaust Manifolds fail and what happens when they do?
  • Exhaust Manifolds can fail for some of the same reasons as any other type of exhaust part. Heat, thermal stress, and corrosion can produce cracks that result in leaks and noise. When a manifold fails there is a pulsing noise ranging from a soft ticking to a loud booming depending on the size of the leak. The hot gases can burn nearby wires and hoses, causing additional damage. Additionally, carbon monoxide vapors may find their way into the passenger compartment with potentially deadly results. The Manifold must be replaced when it fails.

Reprinted from Dorman's Exhaust Manifold FAQ.

Exhaust Manifold Replacement Tips:
  • Always compare the replacement unit to the original before installation.
  • Always start with a cold engine. Removing exhaust bolts from a hot engine may damage the cylinder head threads.
  • Clean mounting surfaces are required for all exhaust manifolds. See the shop manual for any warnings or special instructions for the vehicle application.
  • Use caution when replacing exhaust manifolds on aluminum heads.
  • Never reuse the exhaust manifold gaskets.
  • Torque all bolts to manufacturer’s specification. See the shop manual for torque specifications and sequences.
  • If the original exhaust manifold is cracked and/or has a blue color, check for a rich running engine or an ignition system failure. If this condition is not corrected, repeat failure will occur.
  • For ease of installation, replace the catalytic converter and manifold as an assembly on the 1996-98 Honda Civic, especially with high miles.
  • Be sure to reuse all brackets and braces. Failure to do so will result in premature failure.
  • Prior to installing the oxygen sensor into the replacement manifold, inspect the Oxygen sensor threads for damage. Failure to do so will result in damaged threads on the replacement unit.
  • Be sure to use anti-seize on the oxygen sensor threads to prevent galling of the threads.

Reprinted from Dorman's Exhaust Manifold "Technically Speaking" Bulletin.

Dorman's Limited Lifetime Warranty is described on Dorman's Warranty Page,
and is guaranteed and fulfilled by your eBay Seller eCarOnline.

Information for Buyers

Placement reference diagram
FAQ & Common Terms
  • Left & Right is the orientation when sitting in the car. Left indicates Driver's side, Right Passenger's side.
  • New Take-Off (NTO) means a quality, low-cost OEM part in like-new condition. See More »
  • New Old Stock (NOS) means a fully-functioning, still-new item which may be dusty from storage. See More »
Shipping Details
  • International Buyers – Please Note: Import duties, taxes, and charges are not included in the item price or shipping cost. These charges are the buyer's responsibility. Please check with your country's customs office to determine what these additional costs will be prior to bidding or buying.
  • Shipping directions left in Paypal Notes will NOT be considered. Please contact us directly if you have a special request. Please note that we cannot accomodate requests such as "Leave on Porch"; such directions are better directed to your local delivery person.
  • Free Shipping, when advertised, is only for destinations within the contiguous US. All other destinations must pay additional fees.
  • Shipping Method may be changed or upgraded by request, but may involve an upcharge. We reserve the right to change to a method of comparable speed without notice. See More »
  • Handling Time may be longer than advertised for special-order items and items bound for international and non-contiguous destinations.
  • Backorders may occur. We can confirm stock any time on request. In the event of a backorder, we will contact you promptly.
Troubleshooting Problems
  • Payment Delays Unpaid item grievances are initiated within 14 days when payment has not been made. Payment may still be made after grievance is initiated, and will cancel the grievance.
  • Adjustments or Cancellations can be made without penalty as long as item has not yet shipped; just contact us!
  • Item Arrives Damaged Please preserve the package and contact us as soon as possible with a photo of the damage. See More »
  • Lost Package If you suspect your package is lost, contact us so we can investigate or send a replacement.
Quality Assurance, Returns & Warranty
  • Returns & Exchanges Accepted for any reason within 30 days for unused & unaltered products. Fees may apply.
  • To Initate a Return or Exchange, contact us BEFORE shipping & please read our full return policy: See More »
  • This Item has a Warranty: One year against manufacturer's defects. Initiate a Claim »
  • Disclaimer: We do not reimburse any installment or mechanic fees; returns and warranties cover only the value of the part itself, no associated labor.
Customer Service
  • Hours Live customer service is available Monday through Friday from 9am to 5pm EST, excluding US National Holidays.
  • Email should be directed through eBay's "Ask a Question" link. Responses within one business day.
  • Phone calls should be directed to 888-533-9119 (Toll Free).
RNB-674-506