These coil covers were built in 1987 and are still in use today. They fit the S Scale America Thrall gondola, available from Des Plaines Hobbies. This is a relatively simple kit of high-quality resin, with a few separate parts as well as decals included.
Prototype photo of coil covers on a Thrall gondola in 2019 (photo by Jim Kindraka; used by permission).