The 311D is a modernized version of the Soviet diesel locomotive M62, offered by Newag in Poland. Most rebuilds are based on Polish ST44, but some also on the East German V 200. Only the frame remained unchanged and the bogies and traction motors were reused, but modernized. The engine is a more efficient 7FDL 12 from General Electric.
The body of the locomotives is totally new and resembles American road switchers with hoods and outside running boards instead of the old central gangway. PKP uses 27 of the subtype 311Da on the LHS line with Russian broad gauge. The standard gauge variant is only used by private operators, most of them by DB Cargo Polska.