SO - After many of hours trolling the forums across the internet. I came to the conclusion that this time when i replace the Rear main - i would use a genuine ISUZU seal to prevent ANOTHER leak.
I had my clutch replaced 20k ago and at the time had the rear main replaced (Which was leaking) - They replaced it with an aftermarket ONE piece seal.
This Aftermarket seal is a double lipped seal that is easily pushed in with your fingers and/or small amount of hitting with blunt chisel /rubber mallet.
The GENUINE isuzu seal is what at first glance a one piece seal. Upon further investigation it would seem it is a two piece seal. In the third picture you can see the inner and outer ring seperated by what seems to be a soft foam of some description.
the inner ring easily rotates around within the outer. This seal IS NOT able to be pushed on with my fingers. And due to the Cost (95$) and the construction of the seal i am not prepared to persuade it with a rubber hammer to have it leak again in 20k.
The picture with the boxes was taken from the old forum and my numbers matched the new seal in the plastic bag.
On monday i am going to try and track a tool hire company (and do it myself) or a engine rebuilding shop that will install the seal for me.
Brisbane ISUZU said they could install the seal but takes 1.5hrs at 135Per hour. They charge 135 PH from the depot (about an hour from my house).