I got all my steelback wood kits from Bert's in Denver. I know they were made somewhere else, but they had everything I needed. As Vern said, there is a lot of fitting required.
It is a steelback, there was never any top material on the back. There is also a strip of moulding around the top on the back that stops the material from going down the back.
I am looking to buy a complete wood kit for my 1929 Steelback Fordor. I have seen a couple different sites that sell them, which company has the best kit available?