Not much-The rubber on the support was apparently making contact with the rock guards/shields and transmitting the vibration to the body. Cut away some of the offending stuff. Also the flex disc can be installed two ways, the rubber is thicker between two adjacent bolt holes and apparently one way is incorrect, a good picture is on page 186 in the Haynes 740-760 manual. Also there are arrows on the disc to show you which direction the bolts go. A balance issue possibly?
I may try shimming the carrier plate for a little better alignment. So far the droning is gone but I have a very slight vibration,probably from incorrectly positioning the disc.