The key difference is the transfer case. The 4x4 Dakota requires a transmission with a provision for a transfer case to send power to the front axle. The 2WD transmission lacks this feature. Even if the bolt patterns matched (which is unlikely), the output shaft wouldn't connect to the 4x4 system. There might also be differences in bellhousing bolt patterns to match the engine.
Therefore, you'll need a transmission specifically designed for a 2000 4x4 Dodge Dakota with a 3.9L V6.
