242 input shaft/gear swap?

Someone throw me a link or give me a quick description of how to swap my 242 21 spline input shaft/gear to a 23 spline. I searched but only found questions/answers that didn't give the descrition of the process, just that it needed to be done.

Here's one that has some details on swapping the input shaft/sun gear between a 249 & 242; swapping between two 242 cases shouldn't be much different.

http://jeephorizons.com/tech/tcase.html