These "Nystrom" trucks were used by the Milwaukee Road under their Hiawatha and Olympian streamlined passenger cars. K.F. Nystrom was the Milwaukee Road's engineer for car design for many years (and later their chief mechanical officer). Regarded as perhaps the foremost authority on trucks in the United States, his trucks had a distinctive look unlike any other. These trucks employed coil spring suspension in conjunction with hydraulic shock absorbers and sideways stabilizing devices. There were dozens of rubber mountings in the trucks as well as in the couplings and buffer plates (thus serving to virtually eliminate vibration and noise).
Kato makes Nystrom trucks for their Milwaukee Road Olympian Hiawatha cars -
Nystrom trucks are also available from shapeways.com (based on 3-D designs supplied by NLA Empires). They are comprised of "UV Curable Acrylic Plastic". Wheelsets and couplers not included.