The penrite wasnt that much more than the castrol from memory?  The viscosity range is not as much as the castrol too, not sure how that would affect things?
 
mr2qik, do you have a link for the listing of stockists of the easy shift oil?  I could only find listings for various fuels?
 
Cheers
 

Picked up 4 litres today of the easy shift from Welshpool.  Will report back once the car is running!!
 
Cheers

Car is running, caltex gear oil is performing well, shifts are great, even when cold (well ambient temp ~35 degrees).  
 
Factory LSD turbo box, took under 4 litres to fill.
 
Cheers