righto lads, FYI it turns out the length from where the stick seats into the carrier that's locked by the circlip to the ball/cup at the end of the stick is shorter than a stick from a RB25 box, i found this out by comparing it to a mates set up.
I am not sure where the stick that i have came from but it is defiantly shorter therefor why it falls out when selecting gears.
So if anyone has a rb25 gear stick i am looking to buy one.
Cheers for all ya help.