I bought a pair of the warbird PIKO hoppers as shown on page 95 of the 2020 PIKO catalog and added Kadee body mounted Gauge 1 couplers to them.
As Fred suggested the anvil end of the Kadee gauge was used to get the height needed to mount the couplers. Luckily the height was exactly that of the bottom of the frame and the detail in the center of each end of the cars.
The trucks were removed and dissembled. All but 1/4 inch of the draw bars used for the redundant hook and loop couplers were removed. The trucks were reassembled and set aside to make mounting the coupler boxes to the frame easier.
These particular cars had a drop in the bottom of the frame near the bolster. But the frame and the bottom of the detail in the center of the cars were a 1 inch flat space on which the coupler could be fastened.
The protruding screw pocket at the back of the coupler gear boxes were sanded flush with the back of the gear box. This would minimized the amount the couplers would protrude from the cars.
I assembled all the couplers and glued the top of them to the frame. Using the hole in the center of the gear boxes as a guide I drilled a 3/32nd hole in the frame. Then fastened the coupler by threaded a half inch 4-40 bolt through the frame.
With the couplers in place I fastened the trucks back on the car with the 1/4 inch the drawbar nubs facing the center of the car. They couplers worked very well on the 8 foot diameter curves and PIKO switches on my switching puzzle layout.
