According to the almighty Tabellenbuch, the 230 SL had two versions of the manual transmission. The first version is listed in Tabellenbuch 1966 which I don't have. The second version, in Tabellenbuch 1969, shows that the 230SL 2nd version, the 250 SL and the 280 SL have the G 72 transmission. This same transmission is also in models 230S, 250S, 250SE, 300SEb, 300SEL, 300SE/C, 280S/8, 280SE/8 300SEL/8 until May 69. There are, however, differences in the internal gear shape (but not ratios) and in the diameter of the shaft at the front cover depending on the type of clutch used, i.e. membrane spring or coil clutch. See footnotes in Tabellenbuch.
Automatic transmission is the K4A025 up to May 69, installed in 200, 200D, 230, 230S, 230SL, 250S,250SE, 250SL, 280S/8, 280SE/8, 280SL/8, 300SE/C, 300SEb, 300SEL, 300SEL/8.
Klaus
1969 280 SL