The 5th detent is not assigned. The truck shifters don't even allow movement into that position.Not nitpicking - This is a great idea and great that you are trying to keep it looking OEM - But I think a 6 speed would really improve the package. As mentioned a 6L80 has 5 detent positions. The LR automatic shifter isn't very complicated, I have not been into one is some time, but I remember the rooster comb (detent profile) being a removable piece. Maybe create a new profile with the 5 detent positions and produce new labels? Having a clean looking OE solution would be very cool. If you could integrate the tap shift button into the solution it would put you a cut above anyone else doing this sort of thing.