On Thursday, January 24, 2019 at 5:50:57 PM UTC-8, pyotr filipivich wrote:
whit3rd on Thu, 24 Jan 2019 12:34:05 -0800 (PST)
typed in rec.woodworking the following:

It is also possible that the manufacturer uses the exact
same shaft for other saws, and their other flange washers
will fit and work perfectly...

It maybe required, but that doesn't mean the company is going to
keep supporting those tools.

The first four digits of the serial number are the same for all those replacement
parts; but, the SAME PART is probably available by a different serial number
to 'repair' four or five similar saws. The long serial number enables warranty/inventory
controls at the manufacturer, maybe even down to batch level, that no user
should have to care about.