Complex sentence: The first batch of fifty locomotives were delivered in 1972 with the first locomotives arriving in March, numbered 35-001 to 35-050, followed by a second batch of twenty in 1973, numbered 35-051 to 35-070.
Split into simpler sentences: The first batch of fifty locomotives was delivered in 1972, numbered in the range from 35-001 to 35-050, with the first locomotives arriving in March. These were followed by a second batch of twenty in 1973, numbered in the range from to 35-070.