Ah yes another thread about jeep noises, I've combed through multiple threads but none matched the current problem that I'm having so here we are. I have 2009 JK X 2dr with 109K miles. It's currently making a rotational pinging/clunking noise (sounds like metal on metal) during both acceleration and deceleration that is coming from under the center and rear of the jeep. It's louder and more prominent in 1st and 2nd gear while accelerating and is accompanied with an extremely noticeable vibration from the rear end starting at around 1500-2000rpm. If my foot is down on the gas I get vibration but as soon as I let off it stops however the pinging noise can still be heard. I'm thinking it might be the rzeppa joints on the driveshaft or something else driveline related because if I am in park or neutral and rev the engine I hear nothing. Although not the best, I attached a video that has the sound in it if you turn your volume up. Any opinions or suggestions are highly welcomed, thanks.

 

Easy way to diagnose that driveshaft is to remove it. I think it's 8mm bolts (x8) at the transfer case side and 15mm bolts (x4) at the axle side. If it's indeed bad, you'll have to pull it to repair or replace it anyways. There's no harm in removing it and I've not had any adverse reactions from pulling it and reinstalling it however it fits (no paint lines to mark where it came from).