On my 1997 Isuzu 3.2V6 there are 2 threaded holes near the outer rim of the pulley. I made-up a steel bar to lever against bolts screwed into those. Links to pics below.

Some folks use the starter to 'crack' the retaining bolt loose.

If you have a manual trans you may also find that it will hold the crank for you with the park-brake on.

Here's a link someone hosted to download my timing-belt DIY PDF for the 3.2V6 SOHC

http://www.datazap.net/sites/Australia4W...r_Pump_rev2.pdf

Original post was here: http://forum.australia4wd.com/index.php?showtopic=7463

For folks with DOHC motors - very useful info here: http://forum.planetisuzoo.com/viewtopic.php?t=16972

Aussie 1997 3.2V6 SOHC 6VD1 Holden Jackaroo SE (Isuzu Trooper/Bighorn/Monterey) 5-speed manual, rear LSD, front Lokka (manual free-wheel hubs).