Loosen Pivot Bolt at the bottom (14mm) - easier to access this from the bottom after taking the undercover off (4 x 12mm @ 21ft-lbs)
Loosen Lock Bolt at the top (12mm)
Tighten Adjuster Bolt (running left to right) to tighten belt(s). (12mm)
Drive belt deflection is:
New Belt: 6 - 8mm
Used Belt: 8 - 11mm
A belt is considered used once it's been in use for 5mins of the engine running.
I found the torque setting for the Pivot Bolt and the Lock Bolt on ih8mud at the following link:
http://forum.ih8mud.com/80-series-tech/180598-alternator-smog-pump-use-lock-tight.html
Pivot Bolt: 43 ft-lbs
Lock Bolt: 15 ft-lbs
Bare in mind these are probably for a Petrol 80 ... hence the values might differ for a deisel.
Difficult to get a torque wrench on the lock bolt though.
For newbies and people with OCD, like me, torque settings are a good way to avoid over tightening bolts hence causing further problems.
But like Paul and Andy advise use a spanner to get a better feel of how much torque you're applying.
After reading this thread I've just done my belts today, and removed all the squeaking - thanks guys!
Careful how much you tighten the belts though - if they are too tight then this can cause problems with the bearings in the alternator and cause premature wear!
Hope this helps.
IQ