Outer Limits 4x4 Board

I am in south east QLD and looking to reduce the ratios in my HJ60...I know what ratios are available...just wodering where the best places to get them from would be...

and is it an easy job to do yourself...I have some mechanical knowledge...but is it out of the DIY hands.

Heaps cheaper to import them yourself. Try http://www.tomsdifferentials.com. $150 USD for 4.56 crown wheel and pinion sets.