From Myron's info here's what my 40/2-R means: 40/2 is 29mph engine ( Type 255 engine somehow tweaked from 255 engine that only goes 25 mph- possibly slightly higher RPM limit). R is regular transmission NOT the 2 speed. There are different cables and an anti-back pedal mechanism on pedal sprocket for the 2 speed, beside the obvious pulley difference; none of which mine has, so mine is correct as a single speed with slightly faster engine. That's what I like about this hobby- always something new to learn and to share it with anybody that is interested.