'Cause the 340 was only made for like 5 years, and in half that time they were detuned/smogged out by the EPA. So for like 68 till early 71 (or something like that, I know Im in the ballpark with the timeline) the 340 engines were the best ones put out by the factory. A 73 340 is still good to have , but it is not the same monster as an early 340.