If anyone happens to be concerned about parts for the Aristo-Craft GP40, I designed replacement truck sideframe spring hangers for it as well as the cab visors. These 3-D print parts are implement by and available from Colin Camarillo.
See: CamPac Replacement Hanger for Aristo GP40 Truck Installation Guide
See: Aristo-Craft GP40 Cab Visor & CamPac 3-D Resin Print Replacement
These miscellaneous parts can be obtained by contacting Colin Camarillo via his website.
-Ted