I am repacking the bearings on my 66 but it had been converted to disc brakes many years ago and I dont know for certain what year. I looked at the 1972 shop manual and looked for a spec or even how to repack the bearings and all and didnt see alot of info for the c10, there was some more details in the 4 wheel drive K series section though.
I watched the eric the car guy video on tapered wheel bearings and followed his instructions on that nut and that it should be loose not tight. At the 23 min timestamp he shows this. This seem right to you all on the C10?
https://www.youtube.com/watch?v=ccsbu2hT0MI