I was under the impression that the seat spring bases are the same part # on 116,123 and 126 series. You might have to transfer the seat rails and sliders from your old seats to the underneath of the 116 seats.

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1979 240D, 4spd manual, Power Sunroof, manual windows, 147k miles, Pastel gray/Black MB Tex.
1991 300D 2.5 - Smokes like it's on Crack!