The most probable cause is that the clutch is either not releasing; master/slave cylinder not working, or the clutch itself is damaged.
It is best to remove the torque converter to change a gear box on a Nissan. This will help there to be a smoother time adjusting the gear box.
because that is just the type of car that does that.
For a 1988 Nissan 300ZX Non-Turbo, the recommended gear oil is typically a 75W-90 viscosity gear oil that meets API GL-4 specifications. It's important to check the owner's manual for any specific recommendations or requirements, as some models may have variations. Ensure that the oil you choose is suitable for both the differential and the transmission if applicable.
I have a 1993 Nissan Sentra. It jerks in first gear. While changing to 2 - 4, it runs very smoothly.
The recommended type of gear lube is a GL4 in a viscosity of 75W90.
A FUALTY SPARK PLUG
the gear would be 3.55
This is not a hard job, but will take some time to do. You will need an impact wrench and a gear / pulley puller; do not even attempt this job with out these tools
A manual transmission swap is fairly involved. I apologize but I don't have enough time to get into it. There are some good articles available, they should be searchable with google or another search engine.
You might try to double clutch between gears if you know what that means. Sounds like a synchronizer is out. Contact me if I can help.
THE INHIBITOR SWITCH TELLS THE ECM THAT THE TRANSMISSION IS IN PARK OR NEUTRAL AND SAFE TO START THE MOTOR SOIT ISNT IN GEAR IT IS ALSO CALLED THE NEUTRAL SAFTEY SWITCH AND IT IS LOCATED ON THE TRANSMISSION
Yes, the Nissan GTR does have a gear noise which is a very common phenomenon.