Engine RPM is on the outermost edge of the top of the tach. The numbers read CCW around the dial with the extended "block" just past 16 (1600) being where you would place the needle to achieve 540 rpm PTO speed. All the other numbers on the dial represent ground speed at a given engine RPM and gear.
The upper band being ground speed for gears 1 through 4 and the lower band gears 5 through 8.
