I agree with Ross. For most driving, even with modest freeway driving, the simplicity of a 3 speed auto with modest rear end gears is a tough combo to beat. Lower cost is also a plus. I am running a C4 behind a 289 with 3.25 gears and it gets decent mileage (16 around town), good power, and runs at 2150 rpm on the freeway at 55. Simple but works fine for me.