That's a sure sign that it's worn out. For some weird reason, Ford put a MD (Medium Duty) Trac-Loc in our cars. I've completely destroyed 2 of'em so far.
Are you lookikng for a stronger
Track-Loc, OR a different & stronger differential?
I currently have a (regular) Auburn Cone in my car, and I would NOT recommend it to anybody. It's a mystery to me why the Mustang Boys love the Auburn so much. Maybe they don't make as much TQ as we do. My car is able to overpower the cones. When I get on it, I can feel the cones slip about 1/2 turn before the car starts to move. The Auburn Pro has more bias pressure & is better suited to our cars, than the regular Auburn Cone.
I'm seriously considering switching to a Detroit Truetrac, (
http://www.detroitlocker.com/DT.htm) It's a Worm/Wheel design (gear-on-gear). I like the fact that there are no clutches or cones to wear out.
The Torsen (
http://www.torsen.com/) is also a gear-on-gear LS diff.
68COUGAR