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