Hello, I have a 2006 Xterra SE 4x and unfortunaetly no limited slip differentials. I'm looking for a rear diff limited slip. My owners manual does not give me the gear ratio and I have been searching online and found several different gear ratios. How can I find the rear gear ratio with out removing the rear cover and counting the teeth? Also can you take just the carrier assembly out and switch it so your gear ratio remains the same? The prices for used differentials on line is running $800.00 to $1200.00 for one with the off road package so maybe the best way to go is to buy after market and just get the carrier if possible. I'm not sure if I need the off road package to get limited slip or how Nissan builds this. I would like to change the rear and not the front there fore not having to switch to 4 wheel drive as often.