Tj,
I am afraid I have bad news for you as I have tried to change the auto shift stick on my exy and after 3 hours of labour dismantling everything around it by the auto electrician it turned out that the whole thing is one piece and attached to the transmission and can not be separated.
I then went to Nissan and asked if they can change it for me and they said it can only be done if and when I get a new transmission
Sounded pretty bad design to me but the whole thing inside and under the gear stick is plastic parts.
It is not possible to change the factory auto gear stick to anything else and I had a very nice replacement in hand with an overdrive button as well.