i just changed my rb20det clutch this weekend. who ever said the rb20det use the 300zx na cluthc is totally wrong. the rb20det uses 225mm clutch and the 300zx na uses 240mm clutch. you will need to get the ka24de clutch kit. now i need to return the damn 300zx na clutch kit.
i urged you to change the clutch before installing the engine into the car. it's a b-tch to install the clutch when the motor is already in the car.
you confirm the the size here,
http://www.nolimitmotorsport.com/prod/NH03SBMC