In 1932, the Est started to modernize their ten-wheelers of the series 11S, originally numbered 3103 to 3280. The most visible changes were rectangular smoke deflectors, a chimney with greater cross section and four-axle bogie tenders. On the inside, there were changes between the individual locomotives. Most had received Worthington feed water heaters, others from ACFI and some from Dabeg. Concerning the injectors, some had them from Metcalfe and others from Thermix. The boiler pressure was increased from 16 to 18 bars. Now they had an indicated output of 1,250 kW or 1,700 hp at the wheels.

The rebuild of the complete series of 178 locomotives was finished in 1946. The non-rebuilt locomotives were designated 1-230 J and became 1-230 K when they had been rebuilt. Thanks to their axle load of less than 20 tonnes, they could be used nearly everywhere. While the first withdrawals began in 1950, twelve were further modernized, converted to oil firing and provided with a streamlined fairing for the special rubber-tyred Drapeaux express trains between Paris and Strasbourg. They covered the 504 km in five and a quarter hours. Soon they were replaced by Pacifics. The last ones were withdrawn in 1965.