yeah but Ive had differential fluid come out brown and murky on other vehicles (like the front diff in my 98 S-10), just because of the function of age of the fluid,operating temp, exposure to moisture/condensation and time. Never had any effect, nor did it cause me any worry. I dont necessarily have any indicator that there still is any problem after the rebuild - Ive changed the fluid 3 times since at equivalent intervals since I got the car. The first time it was murky, rebuilt the diff. Since, ive changed it and the fluid has always come out nice and clean.

JMH

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)