Strange clicking noise under hard acceleration

[benfbuilder]

Hi all, . I have a 2001 E53 4.4 with 150k 01/01 mfg date. When I accelerate hard from a complete stop I get a few loud clicks (2-5) then it goes away. It only happens from a complete stop, not when already moving, or above 10-15 mph. The sound is like a loud torque wrench and it comes from the front of the vehicle near the trans or diff maybe? Hard to pinpoint. I have just replaced both front cv axles with new ones and drained and filled both differentials with mobil synthetic ls 75-90 gear oil. Maybe it's the flex joint connected to the front diff? Or is it a trans issue? Broken input shaft? I have researched for hours and could find nobody else with this issue. Any help would be greatly appreciated.