Could try looking through the forum for the correct vehicle section & post in there, you will always find a bit of back lash
the halfshafts/diffs ect how much is too much.....I thought nocking was to do with archery. If its knocking there's a problem
pull the shafts check the outer flanges & splines for wear tis common problem. Now the shafts are out you might as well
remove the prop & pull the diff. Have fun & welcome to lz.