I would drive my 1978 FJ40 more (don't have 40,00 miles on it yet) if it wasn't so wound up at 50 mph. I have thought about installing one of the "overdrive units" available on the aftermarket. Has anyone done this that could give me some results they realized? What does it do to rpm's at 50-55 mph. Has anyone checked miles per gallon on the road with one of these units?