Why did the peterbilt truck company discontinue the production of the peterbilt 379?

The big nose Pete was a thing of beauty, but the signature big square nose didn't do anything for aerodynamics, also spelled fuel mileage. The newer narrow nose profile is just plain more efficient.|||It was discontinued for a couple of reasons first off the engines used in that model did not meet the emissions standards for a diesel engine and most importantly the designers decided to do away with it to produce more off the newer model the 389