Lets clear up a few "basic knowledge" things here. First a self locking nut is a SINGLE use item, once it's been installed it will never have the same holding capability it was designed to have, it will also require less torque to turn the nut every time because the friction decreases. If you keep using the same nut and keep torquing to the same torque you over tighten the bolt, over tightening means stretching the threads. Every single time you tighten a bolt you stretch the bolt. For anyone to discredit these statements they don't know what they are talking about. I did a lot of research on the companion and as I mentioned some people had even forgot to engage the lock pin at all, nearly all are using the shim method and as I also stated I have NO DAMAGE to my vehicle using this method, if I was having the kind of problems the OP is having my bed would also be broken.