The succession of dynamo types used is as follows:
-Bosch RJH 90/6 1800 RS 189 (source:
Ersatzteilliste- Ausgabe A, dated 20.06.1936). This is the earliest
reference I found and it was the type used in early 1936. A Bosch
list of equipment used in Mercedes cars (issued March 01, 1943)
mentions RS 189 as the dynamo equipping 1936 cars. The same source
lists the regulator as Bosch SSM 81/ 13Z;
-Bosch RJH 90/6 1800 RS 222 (source:
Ersatzteilliste- Ausgabe B, dated 19.03.1937 and Ersatzteilliste-
Ausgabe C, dated 25.04.1938). In this last source the regulator
is individualized for the first time as Bosch Type SSM 81/ 13Z.
The Bosch listing omits any reference to 1937 models;
-Bosch RJH 90/6 1800 RS 235 (mentioned
in a MB source and also in the Bosch listing as the type used in
1938). The regulator is SSM 23/58Z;
-Bosch RJH 90/6 1800 RS 262 (mentioned
in a MB source as the type used in 1939). The Bosch 1943 listing
mentions that this regulator was also used in 1940-41. The regulator
is still Bosch type SSM 23/58Z throughout 1941;
-Bosch RJHK 130/6 2200 R3P (starting
at car NR 136.050/0001- source: Reparatur Handbuch Ausgabe C dated
1943). The same source mentions that the previous type was RS 262
of 1939. The 130Watt dynamos that superseeded the 90W models were
considered necessary on account of an increased power need (e.g.
because of the introduction of radios) and continued being used
after the war. They are immediately distinguished by the louvered
brush cover and by the "fat" regulator mounted on them,
similar to the one used in early Volkswagens.
Note: An Ersatzteilliste
published 31.01.1941 mentions two other different dynamo types in
gas cars presumably for military use, both of 12V..