Need diff help

[HEM49]

Iv just done the rear crown and pinion on my 2010 d22 2.5, the compliance plate says CA39 but stamped on the crown is 37:8 (4.625).
Iv owned the car since new and had an air locker fitted right away, thats the only time the diff has been opened.
Has the factory fd up somewhere or did arb?

 

[tweak'e]

i suspect that just a paper work error. there is only the odd model that came with 3.9 diffs and they where petrol 2wd.
4.6 should be correct.

if it was changed you would have issues in 4wd due to different front/back ratios