In the early 1960s Lindberg produced a small line of HO model trains. A switcher and an assortment of freight cars were offered, as were freight car trucks that were exceptionally free-rolling. Reportedly Lindberg were among the first to employ Delrin in model products.
Overview 1:
https://hotraincollector.com/lindberg-line/
Overview 2:
https://tycotrain.tripod.com/id34.html
A pair of freight car trucks in rust colored Delrin:
https://www.ebay.com/itm/353912166716