Whaddya mean, you THINK? Of course it's 168 tests. You knew that!
335 is, of course, his 'Aussie Number'. Some real nevilles played for Australia between Steve's debut at 335 in 1985, and the 349 number issued to Mark Waugh in 1991, and the 350 given to Shane Warne in 1992. Come to think of it, Warne qualifies as a neville...