I just got 2 new Dash8-40CWs with the body mt. couplers.
Both of them would not run on code 55 Atlas switches or rerailers.
All the wheels where out of gauge (flange to flange) by .020" to narrow,
causing them to ride up on the sw.frogs & the center on the rerailer.
The wheels side easy on the axles so I moved them out to .301" & they both are running fine now.