Please check notes in each part listing to ensure the Fuel Cap Tester Adapter is correct for your 1999 MERCURY COUGAR with a 2.0L 1989cc 121 engine. GATES & STANT are competing brands, and each brand's Fuel Cap Tester Adapter may be interchangeable. Special restrictions like "California only" or "with sport package" may indicate a Fuel Cap Tester Adapter fits only certain 1999 MERCURY COUGAR models.

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After choosing a Fuel Cap Tester Adapter, click the "Add Part" button. Shipping costs will be shown on the Shopping Cart page. You may use your browser's Back button, or click on "Find More Parts", to find more Fuel/Air parts, other MERCURY COUGAR parts, or parts for a different vehicle. Please try our Interactive Catalog (click red Start button above) for faster searching. Both catalogs use the same shopping cart, so any auto parts you've already chosen for your 1999 MERCURY will not be lost if you switch.