You eliminate many possibilities if it vibrates in park. It's possible that the broken trans mount may be causing it too. It could also be a torque converter that's out of balance or the converter to flexplate bolts could be loose. There's not a whole lot turning in the trans in park, so it could even be an engine vibration. Change your mount first, and then we'll see if it's still there and try to narrow it down.
Frank
Frank