Marble clanking sound, only at idle

Hey everyone, I have a 4.0 WJ with 170k miles. Over the past couple of days, I’ve noticed a strange noise that seems to be coming from the front of the vehicle. It occurs at low RPMs while in drive- mainly during acceleration up to about 20 mph, and again during deceleration around 10 mph. Once I reach higher speeds, the noise either stops or gets drowned out by road noise. Here’s the odd part: the noise completely disappears when I shift into park or neutral. Any ideas on what this could be? I have a few thoughts but would love to hear what you all think.