There's no external "tell" except for the part number sticker that may, or may not be on the unit.
Barring that, your first sign would be when the tranny did not bolt up to the SVX flywheel.
Other than "counting teeth" those are the only ways I know to tell the difference. Unfortunately, the stickers were lost on the Legacy tranny when they cleaned it for re-build. I can't believe that Subaru uses stickers instead of stamping or a metal, riveted plate, for identification.
You can get the part number from the diagram at subaruparts.com
BTW, does anyone need a tranny for a 91 Legacy (non-turbo) with less than 10K on the rebuild?
