WARNING: This page is about a different car, the 2011 Nissan Xterra. However, it is still accessible from the selected car via links, so may be relevant.
Remove the retaining ring from the 2-4 shift fork, using suitable tool.
Remove the fork guide collar and 2-4 shift fork spring from the 2- 4 shift fork.
Fig 1: Removing Retaining Ring From 2-4 Shift Fork, Using Suitable Tool