I have a 40 year old stove we needed a fixed grate #356 for Federal Convection Heater CCL . The part we bought is a 356 but it looks like an A is sort of greyed out. we have no idea how to install this it is 40 years younger than we are which is to say we are 80 can you or anyone out there help us? I have used all my wits to register and I am exhausted. someone please reply so i know where to go