The Dexron III should be fine. I used Esso ATF in my SD and it worked fine. $9.99 for a case of 12, at BJ's Wholesale Club, if I recall. It has gone up a bit.

I can heartily recommend Mobil 1 synthetic ATF: a lot more pricey ($5.99 a quart is typical), but it smoothed my tranny's shifting considerably.

Can't say anything about the rear diff fluid, but I'll probably try the Mobil 1 there also. Someone made the point that using the best lubricant in your MB is a good idea, etc, and for applications like the rear diff, the cost difference is minimal. hope this helps,

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Bob Roe
Lehigh Valley PA USA
1973 Olds 88, 1972 MB 280SE, 1978 Datsun 280Z, 1971 Ford T-Bird, 1972 Olds 88, 1983 Nissan Sentra, 1985 Sentra, 1973 230.6, 1990 Acura Integra, 1991 Volvo 940GLE wagon, 1983 300SD, 1984 300SD, 1995 Subaru Legacy L wagon, 2002 Mountaineer, 1991 300TE wagon, 2008 Murano, 2007 R320CDI 4Matic 52K, some Hyundai, 2008 BMW 535xi wagon, all gone... currently
2007 Honda Odyssey Touring, 2014 E350 4matic