[Rev]

OK, we'll make this as simple as possible.

1.) Jack up one side of the rear axle. Put the transmission in neutral.

2.) Turn the rear wheel if possible. If you can not, you have a limited slip differential. If you can, then it's an open differential.

3.) If you can turn the wheel, the wheel will turn 2 times what the ratio is for one turn of the drive shaft. I.E., 5.6 turns for a 2.80. Incidentally the 2.80 is the most common.

Rev