Is it possible to attach an encoder motor from an NP233 to and NP231 and make the NP231 electronic shift?

 

I do not think the provisions are there to bolt it on. Plus, there likely are differences in the shift sector shaft extension for the different actuation methods.

Besides, why would you want to take a rock solid manual activation system and change it into a problem prone electric one?

 

I have a Blazer with the electronic setup and I need a transfer case, someone local has a NP231 for a really good price. Personally I am not concerned about the lacking reliability of the electronic 4WD because it will mostly be used just for driving in winter and not very often at all. If I was looking at a dedicated 4x4 it wouldn't be an SUV anyways, likely a Toyota pickup or something else more versatile than a Blazer.