[jhv48]

I had a TKO 600 with the .64 overdrive. Hated it. Shifted like a truck and the rpm drop between fourth and fifth made fifth only suitable for high speed (80 mph +) cruising. Can't tell you how many times I missed third gear trying to speed shift from second.
Dumped it and bought one of Levy's super alloy T-5 trannys with a .80 fifth gear. What a difference. Shifts smooth as a normal T-5, easily handles 500+ horsepower, never miss third gear and now I have a useable fifth gear. With my 3.46 rear end and streetable engine, I should have bought this one first.