Complex sentence: The first period of hire lasted from October 1978 until about April 1981 and locomotives were selected from a float of engines in the Classes 33-400, and that were allocated by the Railways for hire to Zambia.
Split into simpler sentences: The first period of hire lasted from October 1978 until about April 1981. Locomotives were selected from a float of engines in the Classes 33-400, and, which were allocated by the Railways for hire to Zambia.