Play on diff - excessive?

[R Warlop]

I have a lot of play on my diff on my Greyhound - this video shows how much I can rotate the prop shaft before it engages the wheels:
   https://www.youtube.com/watch?v=RucgE2bNPK0
   
   John Goose already kindly sent me the contact details of a specialist - but before I go, I'm keen to get a broader opinion from other owners.
   
   Many thanks!

[pjbowman]

For better or worse, that seems to match the play in my Ace diff.

[ivs]

I have the same amount of play on my 55 aceca and I'm tired of hearing that klunk. So,
   I have decided to get the thing out and have it rebuild. Now, does someone have experience removing the diff that can give some advice?
   Thanks
   Ignacio