Thanks for posting this detailed explanation and photos Dave. Your pictures show more about the mower than Greenfield's site does. I hope others will pitch in with questions and comments to make this thread as useful as possible in Outdoorking's archives, since there does not seem to be a workshop manual for this mower.
Dave, I hope you will continue the process and show step by step pictures of building up the replacement axle, and then fitting it to the mower and connecting it. Good work, this is good stuff.