Step1
tighten diff one or two turn and rotate diff against your hand .
Repeat using fewer turns each step until the diff feels tight & you cannot make slip . Test by using two drivers into each outdrive and try to rotate gear by & with a rag to get a good grip.
Step 2
install diff inside transmission & car.
Run the motor at a slow speed and hold one wheel to break in the diff.
Takes about 1 min.
If you can feel the diff free up you will need to tighten it some more and repeat break end until you feel it is tight and broken in .