ravensblade.com has a big scooby transmission chart
lists years and models of USDM and JDM scoobs, with trans ratios, ctr diff info and R diff ratios.
so find out your trans #, (at front edge of trans housing on driver side) check out the chart and you'll have a better idea of what you have and/or what you need.
3.9 r diff ratio common in Impreza Ls and OB Sport 5-spd, 4.11 in RS and Forester 5-spd, 4.44 in automatics and certain JDM high-performance versions.. chart tells which ones were limited slips.
Dave G
PS--be aware that "just bolts right up" is a relative term. the hard parts in a swap may bolt up OK, but it's the wiring and ECU issues that make them the devil to get running right. you need to be prepared for things to get complicated and expensive before you are done.