I have a converted BMW 120i to electric. It's currently got a e90 diff in it - 3:91 ratio. Had a 3:38.

I want to go up to a 4.44 ratio. I know I can get a custom ring and pinion for $1900 AUD then the fitting cost is about $1000 - however looking on eBay I see that the X1 rear diff looks identical. I include the photos. Does anyone know how I can go up to a 4.44 radio for an e87 without the custom gear?

X1 diff: https://www.ebay.com.au/itm/BMW-X1-D...frcectupt=true

E87 diff: https://www.ebay.com.au/itm/BMW-1-SE...frcectupt=true