RDM failure, transaxle failure?

I haven't driven my car in about a week, I noticed today a new symptom and am not sure what it is or how serious :

When accelerating hard from a stand still I hear a loud "clunk" from the rear. If i accelerate slowly from a stand still I do not hear it.

if I am coasting very slowly and "blip" the accelerator by pressing it quickly to the floor and immediately releasing I also hear the "clunk" from the rear.

If I am moving say above 10mph and press the accelerator hard - I do not hear it.

I do not hear it in reverse (I think)

There are no CEL or other warnings lights.

My car has about 19k miles

Has anyone experienced these issues? Any ideas?

Thanks,