Here is a more detailed how to on the rear ends;
Originally Posted by svxfiles
Put both, the stock svx differential, and the Legacy/Forester donor differential, on the clean work bench.
(IT MUST HAVE 5 BOLT SIDE PLATES)
Do they look the same?
Are the driveshaft flanges the same size?
If they are different sizes, mark and remove them, putting the svx driveshaft flange onto the Legacy/Forester donor differential. Torque the driveshaft flange nut to 125-145 ft/lb
Put the differentials, with the driveshaft flanges facing away from you, on the work bench.
Remove the rear differential covers.(eight bolts)
One differential at a time, mark and remove the four 5 bolt side plates.
When you take them off, there are flat spacers(shims)between the aluminum side plates and the steel differential housing.
Keep the two(for example)shims from the right side(passenger side) of the svx differential, with the svx right side plate/bearing cup.
And the one, two or three shims(for example)from the svx left,(drivers side)with the left side side plate/bearing cup.
From the svx, take the limited slip carrier, and carrier bearings, as a unit, and remove the svx 3.545 ratio ring gear. Use an impact wrench if you have one.
From the Legacy donor differential, remove the ring gear and carrier, carrier bearings as an assembly.
From this assembly, remove the 4.11, or 4.44 ratio ring gear.
Take the 4.11, or 4.44 ring gear, and install it on the limited slip svx carrier assembly. Torque to 69-83 ft/lb
On the left side of the legacy differential housing, there are two "bumps" inside the housing opening.
File, or grind these bumps for clearance, so that the Legacy ring gear, now mounted on the svx carrier will pass into place in the donor housing. Protect the inside of the differential with rags to keep it clean.
Rinse it out with gear oil, after you are done grinding or filing.
Take the svx side plates, the svx shims, and the O-rings, and carefully install them onto the Legacy housing, in the same manner as they were installed on the svx housing.
Take your time, oil the bearings, bearing cups, and gears. Be gentle.
Torque the side plates to 6.5-8.7 ft/lb.
Turn the axle flange and feel for binding, drag, or roughness.
There should be "a little bit of play" or backlash, between the ring gear, and the pinion gear.
The backlash should be 0.0039-0.0079"
With the differential as is, take it to a "rear end specialist" to set up the rear end.
He will "pattern the gears" for a fee and adjust if necessary.
If you are comfortable with the feel of them as they are, install the rear cover plate and torque the 8 bolts to 18-25 ft/lb.
Don't forget to add gear oil after you install it.
