thanks to everyone who responded.  I was able to locate the four screws bracketing the fuel tank. They are recessed in holes in the chassis.  Once I knew where to look, shell removal was simple

I was wondering how the shell can be removed on one of the new F7's (I have the F7B). The exploded view diagram does not have that information, and spreading the bottom of shell away from the chassis as with Athearn and Stewart F units doesn't release it.  Any recommendations ?