Transfer case interchange?

The New Process (or New Venture) 231 transfer case, commonly referred to as the NP231 or NV231, was used in a variety of vehicles, including the Dodge Dakota. The NP231D specifically was used in the Dodge Dakota. To tell if the transfer case will work inspect, the mounting bulkhead on the replacement unit to see if there are the same, also check the spline count of the input or output shafts to make sure they are the same, also match the wiring plugs and shift linkage, if everything matches you should be okay. Here are the instructions on how to change the transfer case out. Let me know if you have any more questions or problems I can help with. Check out the images (below).

Yep, you might want to call a wrecking yard, they have special software that can give you more of an idea but other than that you need to inspect and compare.