Could this noise be the diff?

Lexus are rather rare here in Australia so many mechs that have listened to the winding sound in my 01 have just said its the diff.

I have changed back 2 hub assemblies, and have the front 2 hubs, and all 3 new engine mounts in the mail. Ill replace all that then probably the driveshaft bearing if the noise is still audible.
I really dont want to have to rebuild the diff, and from reading around on CL it seems these diffs are very solid and rarely go bad.

 

Everything sounds good when I start it. And when I press on brakes no noise. It’s only when I put it in R or D that it makes the noise

it’s a ‘21 is350 with only 25k miles