The part number for the hydraulic filters on my tractor have been superceded 3-4 times during the time I've owned it. Why do part numbers get updated, it looks like exactly the same filter from the outside. Are they different inside?
Mostly its a supplier change.
Any well constructed electronic parts catalog will include access to the complete supercession chain for any current part with prior part numbers. This is often dealer-only info.There's probably someone in the company whose job is to keep track of the part number change history. In order to increase the size of their department they continually change the part numbers.
That's why places like Harbor Freight have different SKU's for the same item; same 'model', same specs, different supplier.I had always imagined that a company like Kubota might have one or more suppliers for the same part, so supplier A might call the part an X42C and supplier B calls the same part made to the same Kubota spec a Z72D, and when Kubota sells it to me they make up a part number like HH720-12345. I would have thought they'd keep track of which supplier produced which parts by tracking the lot numbers they ship out. So if there are problems with a group of parts they can figure out which lot number and then which supplier they came from. It had not occurred to me they would change part numbers if they started buying the parts from a different supplier.