New Castle...and its easier if you slip it in as one peice. If me and my friend can wreastle and swap clutches in 5 hours,(I am a small person, asking anyone that knows) I think your clutch or input shaft might be off. Try taking the tranny outta the way taking off the pressure plate and disk, try reinstearting the clutch alighment tool and put back on the clutch. That is the only way I could see one of these things not going in. Good luck