It's getting to be time for me to upgrade my 02 Fx4 and I've been doing some looking. A feature that mine has now that I want is a limited slip differential. From what I've been able to gather, Ford doesn't offer them anymore. Now, it seems, they accomplish the same thing using traction control. I've read about "one wheel spin control" that simulates the limited slip by applying brakes to the spinning wheel. I've seen some videos that show it working. It seems that this is different from the traction control system and the electronic locking differential and is always "on". I've also read that Ford has done away with that feature also. I've been trying to search for information but all I come up with is a bunch of really old F150 forums and all they are is a bunch of guys arguing over off topic stuff. Can one of you guys that have a newer F150 (15'-present) break it down for me? Is the "one wheel spin control" still a feature? Does it work as far as simulating the mechanical limited slip? Do I need to get the Fx4 package to get the additional locking differential? When did Ford do away with the mechanical limited slip differential? Thanks.