No prob, let us know how it goes.
I originally popped open my trans to replace the 4th shaft, just to find out where it INSERTS into INSIDE the input sun gear was also stripped out...(I have some pics somewhere if you are interested)
There is no real easy way to see the inside of the input sun gear unless you pull it out, which entails pulling the bands/drums as well...you MIGHT be able to push a new 4th shaft into it and see if it "spins", although my input sun gear was 80% stripped, so it would have been a false "good"...
Good luck and use the 4T65-E manual if you decide to go for it, priceless info there...
This is semi-wandering off topic but I replaced my valve body solenoids 2-3 years before my 4th went out, and it eliminated my slipping issue.
