There are many times manufacturers will change part numbers to improve the quality. If you order the old part number, you may get the new one and you may not depending on the supply of old parts and the disposition code.
Sometimes there are serial number breaks that could make the part you order the wrong one even if you have the correct model.
If you got a part number out of an older parts manual, chances are the part number has changed and you may not recognize that the part you need is actually here.Sometimes OEMs will put different charging systems, air filters, etc on the same model number and you must have the spec or type number to get the right part. We want to assist you in getting the right part the first time.