still have tach wobble problem

[Structure240sx]

since i have done the 5spd swap in 4th and 5th gear at 4k or higher the tach needle will wobble about 500rpms back and forth but still go up to redline. the car will keep gaining speed also. i think it was klattr1, ryan, that said it could be my throw bearing. i replaced that yesterday but i still have this problem. also when i'm at a stop in first and go to take off slowly i can hear a little grinding spinning sound. could it possibly be the pilot bushing? maybe its jsut those gears in the transmission. i would think if it was something other than the transmission it would happen in every gear, but who knows. the transmission does have over 135,000mi. but its been holding 8psi great other than this.

[bcar240]

This also happens on my 240. I noticed that the grinding sound on mine is pretty much always there, the engine noise just covers it up at higher speeds. My tach wobbles a little bit over the entire range. For some reason after I replaced my fuel filter with a 300zx one, the wobbling seemed to lessen, but this probably has nothing to do with it.

[Structure240sx]

i;ve heard that i dirty fuel filter can cause werid things at high rpms. i have a z32 fuel filter thats been on for prolly about 10kmi maybe half of that time i;ve been turbo. so maybe it is a little cloged. still doesnt explain the grinding sound tho