Hi,
on the occasion of the introduction of the new models W108/109 in August 1965 MB announced a so called "Teilmodernisierung" (part modernization) for the 230SL models starting with VIN 12343 (mass produced from VIN 12467, Aug.6, 1965) with several new features (trunk light, new door and window handles, new uniform clutch and brake fluid container, new seat and floor construction, etc.) but without the new introduced 2.5l/M129 engine to discourage any rumors of an new model (250SL).
Today we would call it "MoPf" Modellpflege in New German facelift.
During the lifetime of the 230SL MB changed or add ca. 450 features, up to Aug. 1965 nearly 400 (see Engelen: 250SL ~ 35; 280SL ~75 changes).
...WRe