You can replace just rear portion of the soft top as one piece including the rear windows, I have seen some patch jobs that look ok from a distance either by sewing or applying canvas and glue underneath. I would think that a tear of that sort is from age, the top is possibly dry. Have you ever treated it? You can take it to a shop and ask them to repair, then treat your top, check out the SL forum and look for treatments, Cabriolet Impregnating spray from MB works great.
Good luck!
Brian

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Brian W. Heitman

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