Willowbilly---The best thing about OD is when you pull a trailer or other load you leave it in high and don't cause excessive wear on the gears. You are right about a direct drive top gear being a slight amount more efficient at highway speeds, but face it, most vehicles these days never leave city limits so the OD hardly gets used. To have the same breakaway gearing with a tall rear gear you'd need some steep gearing in Low.