2000 BMW E46 323i
I have a 323i but saloon. I also changed my stock 3.07 to 3.38. A almost direct fit is a diff from 320i M54 (2.2L) equipped cars with manual transmission. Only thing you have to do is to install your 3.07diff output flanges, because those cars have 188 diff but they have 4cyl (small) halfshafts, thus also small flanges. Input flange is 4bolt direct fit on your stock driveshaft. If you want 3.46 diff a 323i or 325i touring manual 5 speed gearbox cars have them. Then you don´t have to replace flanges at all.