I know exactly what you are talking about. If you want new pans the best way to get them is probably going to be to fabricate them yourself. Just get some thin sheet metal, cut to fit, and tack weld it in. Easy peasy. I have seen some people replace the pans with expanded steel so that dirt wouldn't pile up there. I pulled the 12' (4 row) model over many, many acres from about 1966 to about 1980. My dad bought it new when he bought his 3010 in 1964. Pulled it with the 3010, then with a 4010. Even pulled it some with an IH 706 Farmall. In all those years the "pans" never rusted out but were always filled with dirt. I think they built it that way to provide more weight. The model is RWA. Dad called it a "finishing disk" as opposed to a "cutting disk," which was the BWA model. I also pulled one of those (14') over a lot of acres with a 4020. I'm pretty sure this is what you have.

(RWA (full).jpg)

RWA (full).jpg (155KB - 1 downloads)