There is a part number for the dovetail. Click on the link below and then click on dale's car. Cost for the dovetail is $400.00, part number- 92207433
I am guessing since it is not a LPO, then you install yourself, or pay to install. just a guess. I am getting one too - so a firm answer would be nice.
http://www.gmperformanceparts.com/se...o_sitelet.html