We went around with a customer for three years trying to get him to pru in the new style fan. Finally got him to take a 1688 outand shut the back part of the sieve so it would be like his 1680. So impressed was he he bought a used 2388 off the lot mid-harvest. The fan is by far the biggest improvement you can make. Just remember to also put the dam an the back of the sieve to.