The South African Railways Class 1 4-8-0 of 1904 is a steam locomotive from the pre-Union era in the Natal Colony.In 1904 the Natal Government Railways placed fifty Class B 4-8-0 Mastodon type steam locomotives in service. Six of them were modified to a 4-8-2 Mountain type wheel arrangement in 1906. In 1912, when the remaining forty-four 4-8-0 locomotives were assimilated into the South African Railways, they were renumbered and classified as Class 1.