727 Transmission Efficiency...

From what I've seen, manufacturers have tailored vehicle horsepower to the stall they can get away with when using lockups. My 94 Aerostar with the 3.0 has an extremely high stall when compared to vehicles of the same size with more power. They use tiny converters compared to say a Dart with a 318/904; and the Dart is probably lighter. You get used to the slipping because it eventually locks up. It needs the overdrive, high stall and the lockup because it needs a 4:10 gear to get going. This is the same type of thinking used by Dodge Truck when they put a 4:10 gear behind a 727. They used high stall converters because the rpms would be way over stall at cruising, but they didn't want a harsh initial engagement caused by the low gear.