Check this link out to see if you can find it there..
http://ourworld.compuserve.com/homepages/stepho/diff.htm
It tells where to find the option code plate on the vehicle and what it means.

Or you can check yourself.
Block the front wheels to prevent the vehicle from moving. Raise both rear wheel off the ground and support the vehicle. Place the vehicle in 2 wheel drive and neutral. Place a line on the sidewall of both rear tires. Place another mark on the driveshaft and on the diff case. With a person on each side of the vehicle slowly rotate both rear tires the same direction while someone counts the revolutions of the driveshaft. When both tires have made a full revolution the number of driveshaft revolutions = the ratio. The ratios are far enough apart that you should be able to tell if they are the same or different.