That leak looks like it is coming up higher yet? Either getting flung up there or is leaking higher up. Looks like engine oil to me. The axle grease is a heavy sticky shit, and should fricken reak to high heaven. Grab and try to pull apart the boots and if its torn you answered your own question.
Mods: ZZP stage 3, 2.9 pulley, prefab pcm, 60lbers, AEM gauges, KandN CAI, SPEC stage 3+, ZZP S3 heat exchanger
ZZP long tube header, Strut bar, ZZP rear mount, Progress rear sway bar, Redline Tuning hood struts freshly installed.