I think I found my own answer. After reading a ton of old posts I found a thread titled [B]99 S500 Transmission[B] posted 8/31/04.
Gilly responds with an actual copy of a MB service document on the 722.6 "life time" transmission. It makes a brief reference to the fluid being anywhere from dark red to a pale yellow depending on age and temperature.
It also indicates that the color does not warrant a change of the "life time" fluid. The part number given in the MB article is the same as the liter Red Trans. fluid that the MB dealer gave me. Interesting.....so I guess I top off my tranny with red fluid that will mix with the pale yellow already in there.
Art 101...whats red and yellow mixed together.....orange?

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FRED

Daily Driver: 98 E300TD 199K
Hobby Car: 69 Austin Mini
Past Diesels: 84 300SD, 312K
87 300SDL, 251K
94 Chev. K-1500 6.5Ltr.TD, 373K