2016 JKUR, 71k miles, 3.5 metalcloak lift, 37’s, stock driveshafts (will be replacing both in next few weeks), no play in ether of them.

Lately (well since taking my top off) I hear a mild clunk when accelerating from a stop and a pronounced clunk when shifting from P to R. There's no vibration or any other adverse affects that I notice. All suspension components are torqued properly. Tranny mounts “seem” ok.

Anybody have this problem or maybe any idea what it could be? Thanks in advance!

 

Sure sounds like U-joints to me. Not saying that’s it, but that’s exactly what they sound like. Next I’d look at mounts. Transmission, engine etc. Sounds like somethings moving.
‘Maybe have the hood open and have someone look when you shift, and then be underneath while someone shifts, shake the exhaust good when your under there, cant hurt.
Or excessive play in the rear diff?