I made up my diff from the S15 housing (to keep the abs sensor), an R33 Auto 4.36:1 Crown and pinion gear with viscous diff, and R33 stub shafts (leading to R33 drive shafts)
Just remember the shims are selected on assembly so try to remember what order they went. You may need to play around with different shim sizes.
Not a difficult task, but just make sure it all spins freely and doesn't sound like its grinding. I found a set of digital callipers useful for checking measurements.