I am not familiar with an R 60 gearbox. I recently changed an N6 only to find out the output shaft into the rotor was a lot longer than the original. Check that before you make too many alterations. As for the mounting bolts, mine are 3/8 UNC but the holes through the wall are a bit loose. doesnt seem to hurt anything.Gearbox is out on my Gleaner R60 and im wondering if I could replace it with a Gleaner N6 gearbox. Only difference I can tell is different mounting bolt size. Im wondering what it would take to make this work. Has anyone ever done it?