Welcome to the club mate
gs400, is the American version of the gs300.
and as far as i know the gs430 was introduced on the mk2 gs which is 1998 onwards, however im not sure whether the 4.3 was introduced then. and im pretty sure in thinking the gs430 came only as a gs430 and gs430sport. although if navigation was added then it would state in the title of the advert, also, there was an option for mark levinson audio and this would read levin or levinson, those two were options,