Rattling sound from gearbox

[iain_ogston]

My car is making a terrible rattling sound (much like a heatshield rattle) under decceleration especially in 4th and 5th gears, although 3rd vibrates too.  Suspect is the gearbox, although it's all fine when sitting at constant speed or accelerating.

Last week it was in the garage and they replaced the secondary output shaft and a distorted woodruff key on 5th but this doesn't seem to have been the problem at all, since the sound is now louder and much more noticable over the last day.  In fifth it bucks like a bronco as the engine slows to under 2500rpm.

Any gearbox experts got any ideas what this could really be?  (last piece of work seems to have been redundant)

I'll be phoning the garage on Thursday to see what's going on.