I searched around and really couldn't turn up the correct answer on the front and rear diff's. Are they "open" or are they locking type diff's? I'm asking since I am planning on changing the gear oil, and want to make sure that no special additives are needed.

Also, what is the proper fluid to use for refilling the diff's...I'm waiting on a new owners manual for the truck and the dealer hasn't been much help.

Thanks in advance.

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1990 300CE-24
2003 SLK230 (Sport - 6spd)
1995 Ford Thunderbird