Basically, some rubber part that resists torque has given up the ghost. Where there should be rubber squeezing or stretching, there's metal hitting. Not uncommon, but very fixable. The hard part is finding which one. It would be all too easy to throw bunches of money at this and not hit the problem.

It could be an engine mount, a diff mount, a flex disk, a transmission mount. Basically, anything that holds the driveline in place. Probably a $20 part, but first you've got to find it.

Best of luck,

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Norm in NJ
Next oil change at 230,000miles