late 71-73 Mostly HP 383 and 440, the 440 are usually six pack cars, the sell all the time for 275 on fle bay, stupid application also they retard the advance 5 degrees and disconnect the carb solenoid on shutoff, anti dieseling. 100 point car guys absolutely have to have them, The solenoid if you can find it goes upwards of 500!!!!! Hell took a shot for $100 on two!