I'd consider that the shift linkage has come loose or undone, the transmission mount can be compromised....have someone shimmy under there with a mechanics prybar or giant screwdriver to try n' separate the mount or see if it is still cohesive~
you know this is going to require a bit of inspection/attention....have someone shift and watch what happens on the lever end....you could see if at least is connected properly....if it is, the geometry of the unit is being affected by the shift position...should be able to witness this movement~
Looking for a Used Frontier in your area?
CarGurus has 25,174 nationwide Frontier listings starting at $1,995.
Search Nissan Frontier Questions
Nissan Frontier Experts
Related Models For Sale
Used Cars For Sale