axle swap problems

Hi me and my friends swapped out the 7.5 axle for a 31 spline 8.8 out of an fx4 lvl II Ranger on my 05 2wd Ranger. The 2 big issues is lots of noise like a semi truck rear end, especially around 40 mph and when you give it gas (Im thinking maladjusted or screwed pinion bearing) and the ABS/Brake...