Aggravating gearbox noise. 1986 Ninety

Getting an annoying noise that seems to come from the top of the gearbox, a kind of tinkling sound that sounds like something is loose, but not in the oily part of the box as it's too metallic. This develops into a bit of an intermittent screech generally when power is on. The tinkling sound continues even when free-wheeling and its driving me mad, any ideas before I attempt some kind of strip down?

Take out the center seat panel and then drive and see if you can locate where the noise comes from,but to me it sounds like a UJ on the way out.

It doesn't sound like metal bangles being jangled does it? I had this problem when I got above a certain rpm and found out that the box had dropped all its oil for some strange reason. Filled it up and over a few days it stopped

Thanks, does have that type of sound, will check oil but pretty sure that is ok.