I just noticed Kris just posted from Shelby, (it wasn't up when I posted so we must have hit send at the same time. I did not know Shelby sold those parts. I am sure they have better parts than what I have used in the past. (I have never used or seen the Shelby parts but I am sure they must be of much better quality). I would certainly ask about cutting the bell housing. No slight intended to Shelby here.
We have never had an internal unit fail. Even the Viper comes with an internal throw out bearing.
David