I am not well versed on JD tiller model numbers, but the model 33 tiller was designed to fit the earlier "closed frame" hydrostatic drive tractors. This included the 120, 140, 300, 316 with Kohler single cylinder engine, 312, 314, and 317. A shaft is added to the hydro to belt drive the tiller. The lever you see is a clutch to engage/disengage the tiller tines, I believe. A lift rod is required to lift the tiller.
The 318 is the later "open" frame tractor, as well as the 316 Onan powered tractor, 322, 330, and 332. There were 2 hydraulic driven (separate pump) tillers, model 30 and 48 that worked on those tractors. There may be other models that I don't know about. A 3 point hitch may be required for mounting a tiller to the open framed tractors (318), but again, I don't know for sure.