E58 400 plus HP Dart sport build

What's the difference between std and E58 ?
.
About 20 horsepower. The E58 had the 68 340 cam in it. It was a four-barrel motor with the bigger 850 CFM carburetor.
It was the motor that replaced the 340 in the Darts and Dusters and the Roadrunners too. An it was used in cop cars too.
The EH1 360 in the Little Red was a factory modified E58.