My 4t60e is off of a 97 grand prix with a 3800 NA.. The 4t60e was available for the 3.8 NA until 99, and was almost exclusive to the 3100.
If you were closer I'd give you a great deal on a used tranny. But I dont think you'd be too interested in driving more than halfway through NY state to get it lol.
On the right side of the chain you'll find 4th gear clutches and hub shaft.. This is after taking off the channel plate and valve body. These pics are from the 65e-HD trans.. The 60e may be different. Not sure.
Now you take off the clutches and pull the shaft out, the end looks like this. This is what causes no 4th gear/overdrive.
I'm fairly certain the 4th shaft slides into the sun gear at the top of the 3rd gear/input drum. But don't quote me on that. If I get bored enough out here I might rebuild the 4T60E just to see how similar they really are.
Hope this helps
