My assumption is that you are referring to the MG G67/27-5 transmission that was installed in the W107 SLs. The ZF was the only 5-speed installed in the W113 body.
If you were looking at the table on pg 88, that 5-speed with a 1:1 fifth gear was for the 2.3-16 or the 1990-3 300SL.
Jim Villers
190SL, 230SL 5-Speed, 190E 2.3-16 Kompressor