No matter the condition of your 1966 GTO, OPGI has the Heater Cores you need to boost performance and get you back on the road. We currently carry six Heater Cores to choose from for your 1966 GTO, and our Price Match Guaranteed prices range from as little as $4.99 up to $128.99. OPGI offers Old Air Products plus one other trusted brands of Heater Cores 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 Heater Cores in person.