[Jac Mac]

Originally Posted by joyridin'

I can't tell what is wrong with the first shaft, but the second shaft will continue to break due to the change in diameter. That is a high stress zone. The last shaft looks like it wasn't heat treated properly and was too soft. You should be around 50Rc depending on what material was used.

The hardness will somewhat dictate the strength. You could very easily get away with 4340. Personally, the Jag rear end wasn't designed for what you are doing. Stick a solid axle in it and beat the heck out of it.

Joyridin, sorry I might have confused the issue, the pics I put up are not those of the car/original poster, they are from a car that I have been involved with.
however I agree totally with your thoughts regarding suitability of the Jag rearend for drag racing.