The List
There are 96 6 letter words with X as the last letter. The highest scoring is PAXWAX at 25 points in Scrabble, though Words With Friends prefers JAWBOX at 28. 1 of them contain no vowel at all: SPHYNX.
ADIEUXAFFLUXAUSPEXBANJAXBEMBEXBEMBIXBIFLEXBIJOUXBOLLIXBOMBAXBOMBYXBOYAUXCARFAXCARFOXCARNYXCAUDEXCERVIXCHENIXCLIMAXCOCCYXCOMMIXCONFIXCONVEXCORTEXCOWPOXDEFLEXDENTEXDIPLEXDOGFOXDUPLEXEARWAXEFFLUXFORFEXFORNIXFRUTEXHALLUXHANDAXHATBOXHAYBOXHOTBOXICEBOXIMBREXIMPLEXINFLUXISOLEXJAWBOXLARNAXLARYNXLUMMOXMAGNOXMASTIXMATRIXMENINXMUSKOXNITROXNONTAXORIFEXOUTBOXOUTFOXPAXWAXPEGBOXPHENIXPICKAXPOLEAXPOLLEXPREFIXPREMIXPRETAXPROLIXREFLEXREFLUXSCOLEXSILVEXSKYBOXSMILAXSPADIXSPHINXSPHYNXSTORAXSTYRAXSUBFIXSUFFIXSUPLEXSURTAXSYNTAXSYRINXTEABOXTETTIXTHORAXTRIMIXTUTRIXUNISEXVERNIXVERTEXVOLVOXVORTEX