My father purchased a l2 in the fall of '77, since then I don't think he has spent 10,000.00 on repairs. The main clutch shaft has been replaced twice, that same threaded double sprocket on the step side,all belts,the same rubber bushings for the shoe (same as super 27 or 92 ).. The biggest fallback for this combine is most certian a melroe 351 pickup (j.u.n.k )She now has 3200 plus hours,still original seat with no tears, but many farts. As for the jent thinking to purchase a N6, Make sure it has all of the updates upuntill 1984. I just purchaced a R7, we were looking for a N6, but I didnot realize that 3500 engine ran at 2600 (+) rpm, so we decided to go with the R7 {rpm 2390, under load 2200}. The 60 series '87,'88,'89 don't have a boost preasure gauge, I use it as a guideline to set my combine, as for bushles per hour, I'll just say it's double that to an l2, it doesn't like tough or wet straw, but I have seen with my own eyes three trucks, unloading on the run, on the same 160 acre feild, unloading to a 10 inch auger, and I still had to wait with the combine.(barley)..