The rear axle ratio is said to have a certain ratio, say 4.11. It is called a 4.11 rear although the 4.11 actually means 4.11 to 1 (4.11:1). This means that the driveshaft will turn 4.11 times for every turn of the rear wheels. The number 4.11 is determined by dividing the number of teeth on the pinion gear into the number of teeth on the ring gear. In the case of a 4.11 rear, there could be 9 teeth on the pinion and 37 teeth on the ring gear (37 divided by 9 = 4.11). This provides a sure way, although troublesome, of determining the rear axle ratio. The axle must be drained and the rear cover removed to do this, and then the teeth counted.
A much easier method is to jack up the vehicle and safely support it with jackstands, so both rear wheels are off the ground. Block the front wheels, set the parking brake and put the transaxle in Neutral. Make a chalk mark on the rear wheel and driveshaft. Turn the rear wheel one complete revolution and count the number of turns that the driveshaft makes (having an assistant here to count one or the other is helpful). The number of turns the driveshaft makes in one complete revolution of the rear wheel is an approximation of the rear axle ratio.