@Tikker: If swapping an output shaft on a transmission scares you, doing a Solid Axle Swap (SAS) is a whole level more complex.
When swapping the output shaft, you pull apart the 3.0 4x4 transmission, practice reassembling it then pull your 2.3 4x2 transmission apart. If you get it wrong, the worst that happens is you have to get a replacement 2.3 4x2 transmission.
If you do a SAS, you will need to weld parts onto the frame in the correct position for the suspension, the brakes and the steering. And if you get it wrong the axle isn't connected to the truck/the truck doesn't stop or steer.
I'm not saying don't do it; I'm saying understand what you are getting into.