For the introduction of through standard gauge working in 1962, the railways built new bogie wagons and started modifying existing stock.
A 50 ton capacity open wagon was designed. The code adopted was 'ELF' and was similar in appearance to a stretched _E__ wagon.
The wagons were built and placed into service between 1961 and 1964. The wagon numbers for ELF were 1 - 79, 91 and 92.
By 1963, the systems were adopting the last letter 'X' to indicate bogie exchange. All the existing ELF wagons were recoded to ELX_ and new ELF wagons entered service as ELX. The recoding took place until the last wagon done in 1965.