Clunk/ click sound question

I get a clunk/ click sound usually when I go from reverse to drive or drive to reverse. And also I hear the same clunk when your coasting and then step on the gas, I notice everything on my truck, everyone who knows me know it will bother me untill I fix it, just wondering if anyone else has this noise? I have 86k miles I bought the truck used so I don’t know when they last changed the fluid I’m going to change it tonight. It is not the u joints I already verified that you can hear it inside the rear diff. The truck runs smooth dosent howl or anything at any speed or accel or deceleration . I feel like I’m going to have to deal with it unless I replace the diff or rebuild it lol. It’s a 2014 4x4

 

Drive to reverse, slack in drivetrain? or transmission?

Clunk stepping on the gas after coasting is a combo of the torque converter unlocking, up shifting and gas being injected back into the engine.

My clunk happens most noticeably between 25-30 mph. Found if put it in s6 the clunk goes away.

 

I had someone shift the gears while I was underneath and it’s definitely coming from the diff, but its quiet on the highway and street. I was thinking excessive backlash but it’s quiet while running. And it dosent do it all the time