Original sentence: 171721 - 171730.171801 - 171806.Ironically this unit was first delivered carrying Southern livery and the number 170727.It never operated in this form and transferred to South West Trains where it became 170392.Southern has recently gained 170392 from South West Trains.The Class 171 "Turbostar" is a type of DMU which is identical to the Class 170, except for the replacement of the BSI (Bergische Stahl Industrie) coupler with a Dellner coupler.The unit has been reclassified and renumbered from 170392 to 171730
Edited sentence: 171 721 - 171 730.171 801 - 171 806.Ironically this unit was first delivered carrying Southern livery and the number 170 727.It never operated in this form and transferred to South West Trains where it became 170 392.Southern has recently gained 170 392 from South West Trains.The Class 171 Turbostar is a type of diesel multiple unit (DMU) built by Bombardier Transportation (previously ADtranz) at their Litchurch Lane Works in Derby, England which is identical to the Class 170, except for the replacement of the BSI (Bergische Stahl Industrie) coupler with a Dellner coupler.The unit has been reclassified and renumbered from 170 392 to 171 730