I believe that Midwest would be one fo your choices. The frame for Midwest's rear blade and their rake are exactly the same. Theoretically, you could buy the blade and then buy the rake assembly minus the frame and swap as needed. I think Jim McCaun even acknowledged this in another thread.
Your problem will be finding a dealer that will sell that to you. I have talked to two of them and they are not interested in selling anything other than the entire implement. /forums/images/graemlins/confused.gif