On an automobile (especially those produced from 1939 through the mid-1970s), a three-speed manual transmission whose gearshift lever is a column shifter (mounted on the steering column) (R-N-1-2-3).
In driver's education, they used to teach students to drive in cars with a three-on-the-tree, but now the cars all have automatic transmissions.
His old car was a three-on-the-tree. Now he drives a four-on-the-floor.