How much drive take up

With the N/S/F off the gound and in diff lock I have from the 12 oclock position to the 2 oclock position at the whell b efore the drive takes up is this normal also how crucial is it to put the prop back on in the same position it came off I marked the flanges but after replacing the front uj the marks are no longer there it still vibrates like hell over 30MPH any suggestions welcome
Dev