When it says 1990-2002 in the forum subtitle it refers to model year -- not production date. The R129 went into production in mid-1989 as a 1990 model-year car, so you very well could have seen one in '89, 'Rattle.
I've never seen any service bulletins mentioning the harnesses and there were not recalls, but M-B has implicity acknowledged the problem. Many dealers have a policy of replacing the harnesses at a great discount.
Finally, in the earlier post, "first three years of production refers to all 1990, 1991, and 1992 model-year cars. This would be from the very first car produced in '89 through mid-1992.