Land Rover Series 2A Engine Noise

Can anyone help me with this engine noise. It is a clakety sound, like a machine gun which occus at the top of high revs before changing gear.

Once in gear, the engine runs fine in the mid-range for the gear and speed. When revving up before the nest gear change, I get that clackety sound. Heard  the most on top of 2nd and top of 3rd gear.

Here is a short video demonstrating the sound.

Send emails or make comments to give your opinions.

Thanks!
Mike