The first photo shows the original underbody. The two pins holding the trucks to the body need to be removed. A small jewelers screwdriver can be easily wedged between the pin's head and the truck body to loosen them.



When the trucks removed, we can now remove the underbody.



The underbody is barely held in place, so just widen the sides of the body a bit, wedge a small screwdriver in between the body and underbody, and it will fall right out.