My 69 Z/28 was a race car for many decades and the original housing was still in it. With the perches moved a couple times, ladder bar brackets welded on and all of the twisting it had over the years, the thing was looking like a boomerang if you know what I mean.
Numbers were no longer on the tube to be seen as the ladder bar brackets went over the build date numbers with any welds or grinding marks left to take care of any other remnants on the old stamp. Housing was so bent up that I simply sold it for the parts it had in it. The rest was considered junk and looked just like the subject diff does in this post. I think I got $1000 for the sum of it in parts given it had race disks, a spool, HD yoke and an Ultimate cover. The rest in my opinion was worthless after being hacked up, ground and welded upon. I don't know how any original stamp could survive that, and if its twisted as mine was, the value is in the toilet IMHO.