Everybody knows no self-respecting stovebolt will run with a riceburner plug in it! If your parts man can't find a plug listing for your truck, you need a new parts man. If AC plugs were good enough for it when it was new, they'll work right today. As the number goes lower, the plug's heat range gets cooler. AC 45 is the reccomended plug. If you're doing mostly highway driving, run one step cooler plug, a #44. For one that's run mostly short trips, one step hotter, #46, will help keep the fuel and oil fouling under control.
Thr "R" prefix designates "resistor" plugs, not a bad idea if you, or any of your neighbors has a radio or TV in operation. (It cuts down on radio frequency interference.)
Jerry
