Rear wheel/axle play

[Ssiptang]

My 2013 GT makes humming noise from the rear end on reverse and turning.
Today I jacked it up and found some rear axle play. No side to side movement but about an inch of wheel play with loud clunking noise.
Is this within normal range?
Its an auto and previous owner of this car installed 3.31 with circle D 5C and I know he drag raced a lot.
I jacked my 2010 up and compared but 2010 has almost no play(maybe 1/4 inch) until the other wheel starts to rotate the other way.

Here is the vid

 

[Marble]

Looks normal to me.

The noise could be anything from the rear end to the axle seals. Until you tear it apartit will be a guessing game.

 

[techcargt]

I would take the cover off the rear , and look at the spider gears and the shaft that holds them in place .

 

[5lho]

I've seen a lot of 8.8s and this seems like one that's heading for the barn. Open it up and take a look. Also don't forget to inspect the driveshaft before you open up the rear. It might just be an external problem.