for rave
so where is the best place to get it and what exactly should i look for
Or you might want to try this:
Morris Lubricants - Morris Lubricants
It is recommended by them for the R380 gearbox and you can buy direct from them. Carriage is free on orders over £50 which you will be able to go over if you do the transfer box and diffs at the same time and buy the oil for those as well.