Central Valley made them, with flexible ,detailed copper springs, and you probably can get them from the dealers that specialize in out-of- production models. Jay Cohen and Nixons are on the www as( Jaystrains.com) and (nixonenterprises .com).
They are both reliable, and accurate in their product descriptions.
These are the products of the original Central Valley Company(not current firm using moniker) , that made the best trucks ever produced in 'HO' , and they command premium prices as you might expect. They have RP25-101 wheelsets, with blackened brass wheels on brass axles.
Good-Luck, PJB