Autolite 606 – Stock Autolite 605 - 1 Heat Range Cooler Autolite 104 – 2 Heat Range Cooler Autolite 103 Race Plug – 3 Heat Ranges Cooler this is from the ''safely modding your 3800 powered car'' thread. so if the car is stock i would say the 606s but ive heard these dnt last that long but the GTPs like them