Noise from under gearbox/bell houseing

[fliptop]

i have a wonderfull metal clicking noise from bell houeing had alook and can not find a thing lose down  there any ideas.

[Budgie]

Propshaft U/J gone at the transfer box end?

Check both front & rear shafts, chock the wheels and take the handbrake off before you start.
When was the last time the U/J's were greased?
If you think you've found it, drop a little oil on the U/J and take it for a short drive.  The oil should take the noise away but you need to get it sorted ASAP.