1.4 gear box death

[Frankwood]

Hi all 
Just wondering if my assumption is correct
5th gear on my 1.4 was whining slightly (nothing much but sounded cool) 
On a jolly jaunt I selected 5th and all of a sudden the whine became deafening and my speedo fell and stopped working 
I dropped her into 4th. The whine went and the speedo came back to life 
But keeps dying every time I select 5th (and the whine comes back) 

I'm assuming 5th has completely died? 

Would it have disintegrated and have shrapnel in the box? 
Potentially be dangerous to the box and the rest of the gears? 

Not had chance to get it on the lift and take a look yet 

Many thanks in advance

[Rippthrough]

Chances are it'll take the rest out, speedo should be on the diff output however so that's a strange one - it is usually the diff that dies on them though.