They first came out with chrome wheels from REA then reintroduced with black (cruddy) wheels with an added slope back tender from AristoCraft. The motor blocks are separate for each driver axle.
The REA ones have a brittle sounding plastic and the AristoCraft ones, the plastic sounds more dense.
They were based on the locomotives used on elevated city railways in the USA. The cab is large therefore sits well along side other narrow gauge stock.
Walthers catalogue 1989
This Cuban cane loco looks similar