There is nothing special about the oil that goes in those components - is all the same specs and any common mineral diff oil is suitable - the diffs in the 101 are no different in this regard to any other sals equipped landie.  I usually buy what oil is on special at Supercheap or Repco - usually end up with Castrol or Valvoline.  I cannot see why you would need to order anything special in.  
Garry
				
			 
			
		 
			
				
			
			
				REMLR 243
2007 Range Rover Sport TDV6
1977 FC 101 
1976 Jaguar XJ12C
1973 Haflinger AP700
1971 Jaguar V12 E-Type Series 3 Roadster
1957 Series 1 88"
1957 Series 1 88" Station Wagon
			
			
		 
	
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