Land Rover Repair: 03 landrover discovery, landrover discovery, rocker shafts

Question
I have a 2003 landRover Discovery and it has a tapping noise as well i went to
three service centers some told me it was the lifters(Cam folowers), but they
charged a hole lot.Furthermore, i read about just being able to replace the
individual problem lifter alone but most centers won't do it. Is this true? or can I
just replace the individual lifter which i saw cost only $10 for each one.

Answer
First of all, valve train noise can come from lifters or the rocker shafts.  Rocker shafts are $500 each side, and lifters are a full-day project to replace.  Given the amount of work to get at the lifters, it's no surprise you won't find anyone to change just one.  What if you go through all that and you did the wrong one?