Driveline vibration out of now where! Help!

Pinkish Red fluid is a great sign.

Trans mounts get hammered out and the rubber in them goes away setting the trans tail metal on metal conduction sound. So yes check that out, good thing to get done. Time takes it toll on those rubber parts.

You could take your floor jack, a couple short 2x4s and small pad of carpet or cardboard and jack the tail of the transmission up off the rear cross member about a half an inch. Then start it up on the jack stands and run it and see if your noises go away. This could have something to do with things moving while you jacked the front of the car up doing the front brakes.

You might get lucky . . .