The pinion seal on the rear axle is leaking in this truck?

It is not so much the torque spec as you need to measure the preload before taking it apart and then match that when installing the nut. I attached the complete process for you review.

Be sure to pay attention to the note where it says to not back off the nut to reach the preload. In other words if you over-tighten it and then try to back it off it will loosen and cause a major failure. You would need a new crush sleeve at that point.

Let us know what questions you have. Thanks.