There is a metal bracket under the factory radio, all I did was screw the metal bracket holder piece that comes with the kenwood to it and then slid the kenwood in. It did take some time to make sure it was lined up and centered but take your time. Works perfect!
I have the Firehawks on my trac, went with them because of the rating on tirerack, and have been very happy so far. I have only had them for about 4 months but my trac is a daily driver and I have had zero prob.
Nice lookin too on my white sport trac...
hope this helps
Jay