Um, I guess when they delivered our combine in 1998(new) it had two sets of concaves, concave modules, and two "sets" of sieves. For wheat, we have the fin style cleaning(lower) sieve, and the air foil Chaffer(top sieve). WE do not add on the extra finger style extentions, New Holland Support says you lose too much air out of it. ITs a pain in the neck anyway. If you've noticed, there is your main sieve, and then an extention about 1 foot long. That stays for all crops, but the big sieves come out. NOw for Corn and Soybeans, I guess they just call them the Corn_soybean sieves. We use those for soybeans, corn, chick peas, sunflowers, and they do a great job. If you're still needing more information reply again and I'll go into more detail about the sieves and concaves. There is also a trick to switching concaves. I can change them in and out completely in one hour now that I know how to do it. I guess the biggest secret is how to place your boards to support the concave. I use boards the length of the concaves and lay them about 9 or so inches high, and add about another inch or two of shorter pieces to the back, since the rotors angle up from front to back. I just "curl" the concave after getting them on my blocks and lift it right onto the pegs. It helps to be thin, strong and 22 years old I guess, but if placed right can become a pretty quick swap. Hope this helps!