How do I know if I have limited slip axle differential or not?

-My 2002 Ford Explorer v8 4.6L 4x4 needs differential fluid changed now that it almost has 200,000 miles on it, but I checked the owners guide but it doesn't show me if i do or not, I'm not sure if I need limited slip fluid or not because i'm not sure what my truck is equipped with... I have recently bought it so I don't know much about Explorers. Thanks!fluid will not make both wheels spin. a quick and easy way to find out is go out to a gravel road, come to a complete stop, and then punch it. if theres a clean set of parallel lines on the road, then you have a limited slip but if one line has more gravel on it than the other then you more that likely have an open differential. also if you have a regular floor jack you could jack up the rear end up until the tires are off the ground and lightly hit the gas and check if both wheels spin.4x4 is not limited slip good luck on gas money