I wish I could help you. I knew enough to know I didn't know enough so I sent mine out to be done. Seems to me that there was maybe a locating pin to be driven in that held the entire shaft from moving for and aft?
1947.2 GMC 1/2T SWB panel 1947.2 GMC 1/2T long bed 1948 GMC 1/2T short bed