What Joe said is right. Now owned by MTD.
You need to know if its a Horse, Pony, or whatever. And what engine came on it.
If there is a tag on the tine shield, it was probably made after MTD bought the Garden Way company. Otherwise the only serial number is on the top of the gearbox (horse models) I never talked to anyone at MTD who could tell me what parts list I needed to be on by my serial number. So I have had to guess.
So far I have been lucky in that their belts and gearboxes didn't change much, if any. and their electrical did not change much either. Most of the other parts don't get broken.