2006 xc70 manual transmission service

[Tjoffroader]

2006 xc70 d5 6spd manual, m66 I think. So I'm servicing the diffs, gearbox and haldex soon.
I've looked through a few forums about what oil to use and it's very mixed what I'm reading.
So I rang Volvo and I'm quoted as follows for the parts.

Diff oil (angle gear) £34.80 1L per diff. 2 diffs
Haldex oil filter £36.24
Haldex oil £20.16 for 1L
Gearbox oil £24.96 X2 takes 1.9L

Does anyone recommend a cheaper alternative that's is as good quality?
Does anyone recommend I look at doing something else while I'm down there?
Any hints tips etc are appreciated.

[Tjoffroader]

I got 4L of Castrol syntrans 75-90 for the box and diffs £65, and I'm getting the haldex oil and filter from Volvo, £56. I'll be getting some additive for the gbox and diff as it's done 180k miles.