I have a 1688 thats due for new concaves. For our crops (R.S. wheat, canola, oats, flax, & soybeans) we use the small wire mostly but like to use some lg wire for oats and all 3 lg wire for soys. If theres a chance of switching back and forth between wheat and oats I'll leave the sm wire in. I hate changing them in the middle of harvest. I was talking to a guy at Harvest Services in Sask. and he has me pretty well sold on putting in just their large wires and using cover plates for harder threshing crops. Anyone with the crops I mentioned doing this? Also was wondering if anyone has concaves from Harvest Services. I have the specialty rotor and was also thinking of trying at least 12 Gorden bars. Thanks