Cat are dropping the letter suffix from the model numbers. http://www.equipmentworld.com/in-ma...rs-from-machine-model-names-except-in-dozers/
Why have all the (build 04) stuff and not just do it a 745-4 like the Komatsu machines?
probably so they don't copy competitors and stay unique. But generally this thing it looks like "let's just change something so we say we have made a change"