I have a Shelby with a production date in April 66. I have two bell housings in my garage and can't remember which one is correct for the car as I've seen mention of both 157 and 164 tooth flywheels. I assume the correct bell housing is C5DA-6394-A and the other one I have must have been from an old Boss I had C5AA-6394-B. I don't want to get rid of the 164 tooth one if by chance that was a transition piece for a later 66. Any help would be appreciated.