Driveline Vibration

[Accelo]

As a general rule as you move forward in time the transmission first gear keeps getting lower. The reasoning is so the final drive can get higher. If you are pulling a low first gets you moving and the .7 OD Saves you fuel. I added a 4L60 to my 1971 BBC C10 and the highway mileage went from 10 to 13mph. A full 33% increase. Nothing you can do to the motor will make this kind of difference. The added benefit was the interior noise dropped significantly.