The last time I did use that product when I was working on the sunken load centre on conctre wall I have to use the retrofit panel to fit in the oringal load centre one good thing the load centre tub is very good shape no corrosion of I can able see { this is first step to verify it before you can justify getting a retrofit in there } and double check the mesurement to make sure it will fit in and yes IIRC they did send me a adpator ring to fit the cover for it due the cover hold down screws are at diffrent location this product I did use is from CH they do fit in pretty nice in there.
Merci,Marc