Auto Lock or Pulse Vac, how to tell???

[Rat City Ranger]

I look in my owners manual and it has listings for an auto and a pulse vacuum locking hub, this may be a stupid question, but how do you tell one from the other???? I can't see any vacuum lines in weird places, but I figured I'd ask anyways. thanks!!!!!

 

[Jspafford]

If it is the truck in your signature, a 2001, you don't have a locking hub at all. You have a live axle, which means the axleshafts always spin with the wheels.