With a 4.10 axle gear ratio your driveshaft will turn 4.10 times as your tire turns one full revolution. With a 3.73 axle ratio the driveshaft turns 3.73 times to one full tire revolution. The same formula applies with any gears that a JK has installed. The higher gear ratio number gives you greater torque. A down side to a higher numerical axle ratio is top end speed, and to an extent, gas mileage. 4:1 refers to the transfer case. A Rubicon has a 4:1 low range reduction, which means that for every revolution of the transmission output shaft the front and rear transfer case outputs reduce road speed, in low range, by 1/4. Torque is then increased by the same factor.