Valvoline for high mileage transmissions

I picked up some Valvoline Max Life Dexron III, Mercon, the other day (recommended to me at Autozone). It's advertised as "New for higher mileage transmissions." Interestingly, the packaging shows an odometer with 75,000 miles same as my car. Anyway, I'm getting ready to change the fluid, but I'm a little nervouse about using this "new" stuff and may take it back for one of the products on Mercedes' approved list. I'd appreciate your comments. Also, is Dextron III, the same thing across all brands? My Mercedes shop advised using any major brand Dextron II, which I guess means Dextron III.
Jerry