Quote Originally Posted by 02NavyBlue View Post
03 and up has the hardened 4th splines he means ^

You have the 4t65e-hd since you have a GTP. If it's supercharged then it's a hd trans.

If the 4th clutch hub splines strip, you will never go back into overdrive until it's replaced. Also the earliest 4th gear will ever apply is at 45+ so anything below it will be third unless you go past and slowly decel it will stay a bit below 45.
2004 and up have the hardened 4th. Just confirmed this with Scottydoggs.

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