I informed the moderator black993. He is representing this car as a GT , when it is a standard S4. All GTs came with a manual transmission.
Porsche debuted the 928 GT in the late winter 1988/89 after dropping the slowly selling CS and SE. In terms of equipment, the GT was like the 928 SE, having more equipment than a Club Sport model but less than a 928 S4 to keep the weight down somewhat. It had the ZF 40% limited-slip differential as standard like the Club Sport and SE before it. Also like the CS and SE, the GT was only available with a manual gearbox.
http://forums.pelicanparts.com/porsche-cars-sale/886440-1991-porsche-928-s4-gt-slate-grey-metallic.html