Complex sentence: In 1930 one of the Class 8X locomotives, SAR 883, was reboilered with a purpose built boiler and at the same time superheated and converted to a 4-8-0 "Mastodon" wheel arrangement by replacing the leading pony truck with a bogie.
Split into simpler sentences: In 1930 one of the Class 8X locomotives, SAR 883, was reboilered with a purpose built boiler. At the same time it was superheated and converted to a 4-8-0 Mastodon type wheel arrangement by replacing the leading pony truck with a bogie.