The CNW Historical Society commissioned a Superior Brake wheel set almost 20 years ago when they commissioned a special run of the MSTL 53000 series boxcar kit. These cars were repaints and were all green except the underframe, which was black. They had yellow stenciling. The kit and the Superior brake wheel were done by Red Caboose. The CNWHS also sold the brake wheel assembly separately https://cnwhs.org/wp1/product/ho-superior-brake-wheel-set-of-3/   But they have long been out of stock.

The mold exists at Intermountain, who now has the Red Caboose assets. Contact them and encourage them to rerun it.