The 5spd gearbox does not use separate fluids for the front diff and the gearbox itself. On these one only changes the fluid for the gearbox (use a 75W-90 GL5). The rear diff has the same fluid specification requirements. If your car is automatic check the manual for what to do, sorry.
Gear oil LS90 meets AGL-5 performance and is suitable for LSD type rear diffs. Front diff. The front diff in an automatic Subaru is different in terms of lubrication from the manual. Both are at the front of the gearbox, but in the manual the gearbox shares oil with the front diff, while the automatic transmission and diff use different oils.