How can you tell when you need to change your clutch kit in the drive and what parts do I need to change.

The drive will also try to kick out of gear. This will feel like you struck something underwater. When you check your oil, it'll be full of very fine metal. That was you clutch. If you have to ask what parts are needed, then you will need to take the drive to somebody for repair. It takes special tool and knowledge to tear the drive down and reassemble it. This is definetly not something an amature can do.