Hi, Buddy . . . If we're talking about the folding steps for going up to the roof, they're commonly sold for firetrucks and similar vehicles. I got mine from here:
http://www.realworktrucks.com/service-truck-hardware/folding-footsteps-and-handles.html
Stay safe,
Mike
http://www.realworktrucks.com/service-truck-hardware/folding-footsteps-and-handles.html
Stay safe,
Mike