I only found a single part number in the "Parts List Four Ninety and Superior Models dated 1923 for the Four-Ninety models.

Thanks much.   That's a pretty good indication I would think that they may have stuck with the one design for 7 years.

The basic size and shape of the shell is the same for 16-23 490, but there are a couple variations I'm aware of.  1) For the early years, '16- ???, the bowtie emblem was painted on the shell.  There is no recessed area for it.  By '20, the shell had the recessed spot with the enamel bowtie emblem.  Not sure when this change was introduced though, but sometime between '16 & '20.  2) The radiator mounting locations changed around '18 where the early ones with the hydrosyphon cooling system (no water pump and the much larger upper radiator tank) didn't have a couple of the upper brackets, as well as the bracket for the center rod to the firewall was different, also because of the upper tank.

@bill-jusela 

Thanks for taking the time to respond with that very specific information.............Much appreciated........Joe.........