GXD is obsolete old version of XD it stands for Gold Xtra Dimension i believe. i also believe it can be updated to XD i dont actually know the differance as i have never knowingley seen one i've only been told about it.
Goodison XD is what it stood for. Based on the setup matching what Paul Goodison sailed and it was their top of the line package will full harken hardware and top of the line rope, carbon tiller etc. The XD/Race version was more Ronstan gear, dont think it had the carbon either.