If it is still stock Kris
Lift one rear tire and using chalk draw a line straight down from the tire to the ground. Next draw a line from the u-joint in front of the pinion shaft to pinion neck of the pumpkin housing in the axle housing. So at this point the line on the tire and the line on the d-shaft all line up to their reference lines on the ground and pumpkin. Put the tranny in neutral and spin the tire one full rotation while you count how many times the d-shaft line crosses the pumpkin line. 3.5 times you have a 3.55, 3 3/4 times your have a 3.73, just over 4 times and you have a 4.10 (and so on). If the one tire does not want to spin than you also have a limited slip in the rear and will have to lift both rear tires off the ground to continue.