gear box rattle 6 speed

[lovingit]

hi every one. i thought i had a problem with duel mass fly wheel but took the box out today and its ok, i turned the shafts on the gear box to the diff and it ratles like there is some think loose inside you can grab the box and shake it and the same it rattles.
has any one got any idear i`m going to start to strip it tomorrow hope its not to hard can any one give us any idear???