Looks like you got the 6bolt CV flange on the diff flange. Most 95 M3s had the black sheep diff with the CV joint at the rear of the driveshaft. Any other year of the e36M3 will have the same case, but with a 4 bolt flange. The Auto M3s had a 3.38, which is a pretty common upgrade, but as far as taller gearing you may want to check out some 5 series diffs.