Trailer Train - Trans America 45’ Trailer
Walthers Part # 932-39811, p. 184 Walthers 2009 HO Scale Reference
The trucks on the car in question are UIC (international) trucks that were probably unique to the Front Runners. They were used to reduce the weight of the car, thereby saving fuel.
Thank you very much for the information. I speculated they were designed to save weight. The design of the entire car reflects that.