oils for a kf. shocks/diff

[Merc190uk]

HI all

just after a bit of advice on oils

I was told (thaks Ben) but i forgot
something like core 450 for the front and 300 for the rear ??

Also i was going to order black 2.6 rear springs as it was running greens when i bought it and they seem a bit soft.

Aaaand..diff oil, what do you use if running the standard diff ?

thanks for any help
Steve.