I am not sure If my truck came with a Limited slip diff or a locker, It Has a towing package, thats all I know, It Shredds both the Rear tires just fine.. Got a little Carried away last weekend and cut donuts for about 15 minutes last weekend , Now When I make a sharp turn, My whole truck shudders and I can hear the tires fighting the turn, I dont think It is Releasing, feels like I am driving around with a spool.. She's Running Just Fine, except Turns feel...off...., Any thoughts, What does it cost to replace?