Rear End Vibrations/Knocking/Clicking

Local mechanic diagnosed low speed knocking noise and rear end vibrations that occur between 60-70 mph as a bad rear differential actuator. It is in the nose of the rear LSD differential. I do not agree as these differentials are known to be very strong. The torque transfer to the rear is controlled by the clutch packs in the actuator electronically.
I believe that the 3-4 mm or torsional (or rotational) play in the inner CV joints is the issue. What do you think? Actually there is no play beyond whats normal on the inner joint. I have new axles from driveshaft shop on the way.

But this is not really my question. Just the backstory. This past weekend I installed an aftermarket upgraded differential top mount. As well as a Whiteline Sway bar. Car was on stands front and rear. As I had the driveshaft off the car was in first and E-Brake on.

Decided to lower the rear end first to prevent the car rolling back as it was on a minor incline. No issues. Move to front and as I lowered it the rear end made a popping creaking noise a few times. I freaked out. I now realize I should have taken the E-brake off. What could have been that noise? What would break first in that situation where the tires are trying to rotate as front of car comes down? I feel so dumb! But I was tired. That is my excuse. Putting in that differential mount was very challenging due to limited space.

As I drove away a new noise appeared up to second gear at low speeds. Fap fap fap, tick tick tick. If I am lucky it is the CV joint that gave way. I will be putting it back up on stands sometime this week when I can get to it.
Thanks!