I have an old Bachmann Niagra from the eighties and I need to know how the front ofthe boiler is secured to the Chassis.The rear is secured with a short screw that installs from underneath.Not sure about the front.
I hope this is of some use to you. It's on the HO Seeker site:
https://hoseeker.net/assemblyexplosionbachmann/bachmann484niagaradiagram1990.jpg
Thanks!that helps !