If you tell people where you are in Oz it makes life a lot easier to find parts and help.
the amount of work required to replace the whole final drive would be equivalent or more work than just replacing the outer bearing. my d6 9u had the outer bearings failed on both sides of the final drive. i completely dissassembled and rebearinged and resealed both final drives. but i could have gotten away with just replaceing the outer final drive bearings and the outer bellows seals if i wanted to do it cheaply. you can replace the outer final drive bearing without removing the track frame and with out pulling the sprocket off the sprocket shaft.
I have a lot of that stuff. No complete finals though.
What specifically do you need.
the bellows seal may still be intact and may only require new cork gaskets, it is amazing how forgiving that seal design is.