We are north of Denver,CO. All wheat harvested at this time. Averaged anywhere from 10 to 30 bushell per acre. We used our recently purchased 80_81 (SN1547) N6, which did a very good job harvesting the wheat..very little wheat thrown over and clean grain in the bin, no major mechanical problems_interruptions. Our N6 has about 850 hr.s on the combine and 1400 on the engine. It has not been "slowed down", but we were able to run it at about 2500 to 2600 RPM, as opposed to the 2700 to 2800 RPM called for in the owners manual. The cylinder speed was around 900 RPM which worked OK for our wheat. Only "concern" is that the manual called for a concave_cylinder setting of around 5_8 in., but we had to set it at about 1_4 in. to thresh the wheat. We saw in other manuals (like that for a MF combine) where the clearance should be about 1_4 in. Don't understand this difference. Basically the combine is a pretty darn good machine, we are "nervous" about the engine and its rods and bearings due to the "high RPM" problem. Should be able to have some basic inspections done to determine the condition of the rods and bearings. We contacted a Gleaner dealer in Yuma,CO. They were not too convinced that slowing the engine down by recalibrating the injector pump and using a N5 drive pulley was that good of an approachIJIJIJ