4pcs Mercruiser 390 NGK Standard Spark Plugs Inboard 8 Cyl GM Big Block Kit wy

This listing is for 4 Spark Plugs. Be sure to purchase the correct number of plugs for your vehicle.

NGK Standard Spark Plugs are the choice of consumers, automotive enthusiasts, street racers and professional race teams around the world. Produced using advanced materials and cutting-edge technology, NGK spark plugs help maximize engine power and operating performance ride after ride.

• Exceptional ignition performance equivalent to the OEM spark plugs available on many vehicles.
• Field tested durability with a 30,000 mile service life.
• Conventional Nickel center electrode provides a reliable spark with low installation cost.
• OE plug for many applications.
• Precision laser-welded electrode construction.
• Trivalent Metal Plating provides superior anti-corrosion and anti-seizing properties.

• To confirm that this part fits your vehicle, enter your vehicle's Year, Make, Model, and Submodel in the eBay Compatibility Table.
• Many of the parts we sell at Sixity only work with specific vehicles. Please double-check the accuracy of your order before purchasing. Check that the reference number, size, and placement are correct.

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• Your order will be processed and shipped within one business day.
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• Our smaller items are shipped via USPS First Class or DHL, while larger, heavier items are shipped via FedEx Ground or UPS. Some items offer faster shipping for a small fee. Please see the Shipping and payments eBay tab for more details on shipping rates and delivery times.
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• Sixity stands for value, selection, and quality. Our goal is to provide a 5-star shopping experience.
• We give all our customers positive eBay feedback. Please work with us by contacting us here if you have a problem before leaving negative feedback.

• If you would like to return your new, unopened, and uninstalled part:


1. Go to your My eBay page.
2. Click [Buy] > [Purchase History] on the left sidebar.
3. Find the item you ordered.
4. Below the Leave Feedback button, click [More Actions] > [Return This Item].
5. Select a reason. The most common reason is Doesn't Fit.
6. Add details like I tried to install this part, and it didn't fit.
7. Click [Request a Return].


• Returned parts will be inspected, and a refund given within 5 business days if the part is new, unopened, and uninstalled. Original shipping costs and a restocking fee may be deducted from your refund.
• If the item has been opened, installed, or used, we are unable to accept a return due to safety concerns.

Known for our industry-leading Sixity XT and XTA CV Axles, Sixity Powersports helps diehard ATV, motorcycle, and snowmobile riders find affordable - and awesome - replacement parts for their machines. Try our fast shipping today: 99% of orders ship within 1 business day!

Our goal is to provide you with the best possible shopping experience through unsurpassed value, convenience, and selection. We strive to deliver on our core tenets for our value-conscious customer base including free and fast shipping*, a 100% fitment guarantee**, a U.S.-based Customer Service Center, and a limited 1-year warranty on Sixity-branded parts. Give us a try today, and happy riding!

• Free, Fast Shipping*
• 100% Fitment Guarantee**
• 1-Year Limited Warranty on all Sixity-brand parts
• US-Based Customer Service Team
• Always Genuine OEM-Replacement Parts from the Best Brands
• All Parts Ship from the United States within 1 Business Day
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* Free shipping applies to the lower 48 states. Certain items may require additional surcharges.
** We guarantee all parts sold under the Sixity brand will fit the vehicles they are advertised to fit.