The car Ill be installing it into is my 1998 Impreza L wagon, 2.2 w/ 4eat. Checked build code thru dealer and multiple web postings and found it was 4.11. The diff I got the donor diff from was a 1991 legacy ss, from my findings this vlsd unit only came in 3.90, but I spun it a few times and I kept creeping a hair over 4 turns. So I pulled the cover 37/9 stamped on the gear. It's a version 1 vlsd. I purchased new cover gasket, seals and proper axles (91 legacy)