I'm not trying to be difficult here but the term "motors" is pretty generic. There are geroller motors, gerotor motors, gear motors, vane motors, variable displacement motors, axial piston and radial piston motors. Each type has its plusses and minuses. The application matters. Look at our tractors. The drive motor is a geroller style that has a displacement of 13 to 17 cubic inches. The tiller motor is the same type but smaller internally. Motors for the decks and snowblowers have special bypass valving inside them for soft starts and stops. Presumably, the chipper/shredder, Hydra Vac and HydraCutter are similar because they all have rotating masses that don't start and stop on a dime.
Keep in mind that the pumps on our tractors are normally around .62 cubic inches in displacement and pump 9.5 GPM at 3600 RPM. If you want to drive something at certain speed, then a small motor displacement will spin faster and a larger one will spin slower. Gearing can sometime compensate but is not always desirable or possible due to space constraints.
You need to ask yourself whether those motors were actually worn out or damaged. If they are known to be good, then I suggest you get the info off them and find out what the specs are. To me, that is far more useful to know than what you are asking.