http://www.autozone.com/repair_info.htm
Click your way through year, make, model, etc. to engine/timing belt.
You can also find lots of mentions of this in the Isuzu forums if you
search the forums, as the timing belt tensioner is a weak point on
this engine.
http://www.4x4wire.com/forums/postlist.php?Cat=&Board=UBB86
http://forum.planetisuzoo.com/viewforum.php?f=4
http://www.automotiveforums.com/vbulletin/forumdisplay.php?f=240
http://www.pirate4x4.com/forum/forumdisplay.php?f=3