I went from 2.56 to 3.73 gears and it made a big difference in acceleration. The engine runs at 3700 RPM at 70MPH using a TH 350 Trans. <a href="http://www.reiderracing.com" target="_blank">http://www.reiderracing.com</a> carries Precision gears for about $155. According to many sources Precision gears are far better than other brands. Good Luck. Hope this helps.