All the drawings I have that look like my saw show the pulleys, but no information on the size in diameter I assume the bore is 3/4" and the belt is 1/2". The motor and the Large pulley are keyed 3/4" and the low gear Pulley is smaller bore and no key way just a flat spot for set screw.
Assuming the motor came with the unit since it is 1/2 HP and the name plate on it is Delta model T5071 it would be nice to know what the recommended v-belt catalog number is.