All horse tillers have one belt you move the belt too change speeds on tiller
Even the 1st models? There is another thread out there where I brought this up because I thought the same. Cheeto (the OP) indicated he had two belts installed at the same time.
The Horse I tillers had two drive belts which are both installed at the same time. All Horse II and later tillers use one drive belt that is switched between the grooves to change the drive ratio. If both grooves on the pulley are the same size, you need two drive belts. If the pulley has stepped grooves (the outer groove is smaller than the inner groove), you have a one belt drive system.
Tim