Part II.

Replacing the rear differential mount did not cure the problem. It was still vibrating at low speeds. So back to the shop and up on the lift. Watch the parts spin... and there it was.

The u-joint at the rear differential was siezed on one side. So the first side would flex, but not the 2nd, as it turned. Thus moving the rear differential up and down at the front, rotating it enough to tear up the the mount.

We took out the drive shaft. Put the car down and drove it.. no vibration. Cool.

BUT.. not so cool.. you can't replace the u-joints. It's the whole shaft for over a grand in parts... or send it out to be rebuilt for about half that. Or go to a junk yard. I took the middle ground.

Anyway, I hope that this proves useful for anyone searching for this low speed, fast vibration. There's no maintenance on them. Just be aware as your crv ages... 10 years, 115K miles..