I have a 2005 GT with an aftermarket head unit. I am thinking about wireing the radio into the trunk to retain date and time on the DIC. I found this harness on ebay 2000-UP GM Harness to NonFactory Stereo Adapt/Retention - eBay (item 200559085965 end time Mar-27-11 18:07:59 PDT) is this what I need? Thanks