Cement 871 Report post Posted November 10 So I got my 3.91 ratio diff (https://bimmersport.co.nz/topic/69192-wtb-e46-mid-case-diff-or-ring-pinion-373-or-391/) and disassembled it, but the crown wheel looks to not actually measure 188mm as expected 😞It measures more like 168mm which would mean it's actually a small case. Does anybody know if the 188k should actually measure 188mm where I am measuring as pictured ? Stamped code on the ring gear is HK2V PE1 951 0615 which I can't seem to link much back to. @HELLBM are you able to link this item back to the vehicle it came out of or offer any guidance here ?  Quote Share this post Link to post Share on other sites
Eagle 1662 Report post Posted November 10 I thought all 3.91 were small case? Yeah 188k measures 188mm in diameter Quote Share this post Link to post Share on other sites
Cement 871 Report post Posted November 10 Damn it !! That really blows ... chart here says the 3.91 was in the 2.5l N52 model. http://tomic.ba/fs/cjenik/E83 Technik 0307.pdf Quote Share this post Link to post Share on other sites
Eagle 1662 Report post Posted November 10 Maybe there is a small and medium then? There's a guy facebook trying to sell a X3 3.23 diff because it didnt fit his E46, turns out its a large case unlike the E46 one which is a medium in the same ratio. Quote Share this post Link to post Share on other sites
