1996 Subaru Outback differntial

Was the replacement rearend the same gear ratio as the old one?

the replacement was the same from a subaru 1996.. so i belie its the same gear ratio as the old one

so what can i do to stop the noise from the real diffrential or how can i fix it??

The noise your'e hearing. Is it a "howl" that gets higher in pitch the faster you drive? When you turn the driveshaft yoke at the rearend, how much slack do you have? It should only be 3 to 5 degrees, in reality, very little. Where did you get the replacement rearend, a salvage yard? Please advise.

Update: There are 2 gear ratios available for '96 outback:
With 1.8 and 2.2 engines, ratio should be 3.1 to 1
With 2.0 engine, ratio should be 4.11 to 1
There should be a tag attached to the rear cover with the ratio stamped on it. You can compare this # to the # on the front differential to see if they match.

well i bought the differential at a salvage and about the noise its not that high but its a deep noise and as i move the deep noise go hand in hand with the speed.

also the wheels tend to skid a lot as if they are moving fast than the front that is when am begin to move.

so in this case the ratio on the front differential should be the same to the real wheel??
and now that my subaru is an all wheel drive 2.5 engine what would be the best ratio????

The ratio "must" be the same as the front differential. Did you find the ratio tag on the front unit? If the gear ratio's are different, you "WILL" destroy your transfer case!!! I didn't find a 2.5 in the engine list, but motor size is unimportant. Matched gear ratio is.