The FP 7 is a little tight but even that one should not be a problem getting the shell off and leaving the couplers on.
If you do take out the pins, a suggestion is to tap the holes 2-56 so next time is easier.
Jim
Your correct. I have the Atlas/Rocco gp40's and sd35, and the couplers are part of the shell/walkways/handrail assemby. Which makes removing the couplers easier. Just a couple of little latches you need to release on each side, by the fuel tank. Ususally a gentle pry with a small screw driver, the whole shell assembly comes off the frame.
Mike.
My You Tube
What kind of locomotive is this yellow box Atlas the ones i have the couplers don't have to be removed to take off the shell.
Russell
That is a pin and is not threaded. Its a press fit. Try prying up with a small flat screwdriver blade.
It's not a screw, it's a pin, with a head that looks like a rivet. It should be sticking up just far enough that you can grab it with a needle nose, and gently pull it out. They tend to go flying when you get it out, so beware.
This is an Atlas yellow box loco made in Austria, I had trouble removing the coupler to remove the shell, the couplers seem to have a screw but sort of roundhead, not suitable for flathead or philips screwdriver. Any help will be highly appreaciated!