Land Rover Repair: Gearbox and Tappet noise in Disco 2, tappet noise, cam lobes

Question
G'Day,

I have a Disco 2 with 2 problems, the first is a tappet or lifter sound in the motor.  I have been told 2 major causes, worn cam lobes, or rocker shafts, but how can I tell which?  has about 150,000 K on.

Second is a persistant whine from GEARBOX that changes when coasting, acellerating and disappears when in neutral and rolling.  I can change the pitch by moving the gear lever a little, and I was told that previous owner had tranfer case rebuilt, so I assume it is in GearBox.  Is this Normal, as several people have stated?  Would different oil reduce this annoying whine?  Should I add an addative?

Thanks
POCO

Answer
The tapping is almost always from bad rocker shafts.  The steel cup that's pressed into the aluminum rocker becomes slightly loose and causes the rap.  If you remove the shafts you will probably find one or two that are loose.

Some gearbox whine is normal.  It could change by using different lubricant. I would have a local specialist listen to it.