The 7th and 8th digits in that format of part number is a "revision" number. It's possible that your original part has been superceded by this new part. It's also possible that it won't work at all. Did the dealer tell you that the first number is what you needed? or is that the number on your busted part? I don't have my parts program with me, so I can't check it right now.
There used to be a page on the Mercedes Veterens site that explained this, but it seems to have disappeared.
1988 560SL Black/Palomino
1988 300SEL Black Pearl/Burgandy
1984 500SEC Anthracite Grey/Palomino