These are Railex items and are on the valuable side. Railex is a German
manufacturer of high quality Z scale items. Many of their smaller locos are
non-powered and employed a pusher loco (often hidden in a box car or
passenger car body) to move the loco. The problem is that their items are
often very hard to find. Only one dealer in the U.S. carried their line, and
they have a hard time obtaining their pieces. Without seeing your pieces, I
am not sure which ones they are, but they have a limited line so it would not
be hard to track down the item name and release date.