Thank you both so much... especially for the exploded view.  I looked all over the place for that exploded view, but I could never find one.  Thanks again.

Now I need to find those 2 missing screws.   

Strange, I looked inside the hole in the plastic truck mount, under extreme magnification, but didn't see any witness threads.  Maybe they're more like an interference fit, something like a rivet nail, rather than an actual threaded bolt.

I'm very grateful to both of you for your help. 

I think I screwed up.  I took my Bachmann BNSF #3002 (item# 60305) apart some time ago to replace the motor, which went fine without a hitch.  Unfortunately, I forgot how the trucks connect to the chassis.
I don't see any way to hold the trucks in.

I attached a photo of one of the trucks.  The top of the truck is shaped to fit onto a bulge in the chassis, but I don't see any way to keep it there.

You cannot view this attachment.

Any Ideas?

Thanks