No matter the condition of your 1966 GTO, OPGI has the Thermostats, Housings & Fillers you need to boost performance and get you back on the road. We currently carry seventeen Thermostats, Housings & Fillers to choose from for your 1966 GTO, and our Price Match Guaranteed prices range from as little as $4.99 up to $94.99. OPGI offers Mr. Gasket plus two other trusted brands of Thermostats, Housings & Fillers for your 1966 GTO, to help you find quality parts you can rely on. With OPGI's 45-day return policy and thousands of customer reviews, you can shop with the utmost confidence. Enjoy parts delivered directly to your home, or visit our sunny Southern California Showroom & Warehouse to check out our Thermostats, Housings & Fillers in person.