Some observations.
A small Original 1963 1/2 leaflet telling the features on the first Stingray on both sides.
There were 2 1964 sales brochures printed.
First issue showing the color choices which offered Terra Cotta.
Second issue shows Red, but no TC.
The April ‘64 Schwinn Reporter states Terra Cotta has been dropped as a color choice. This is the time Red replaced TC.
This information coincides with the two catalogs.
It seems the colors went like this - Red, then Terra Cotta, then Red again until the end of 1964.
There have been reports of later Terra Cotta Stingrays out there??
The early ‘63 reflector brackets had square ends that folded around the seat strut. These would cut your fingers.
The later version bracket was rounded.
The seat strut on my August 23, 1963 does not have any markings on the bottom legs, but does have the very small vent/drain hole that was used on the first design struts.
Some early version square back struts have a PAT. PENDING stamp and others have PERSONS stamp.
Your strut seems to have some lettering when magnified, possibly PAT. PENDING?
PS, if your able to take the rusted screws out holding the Schwinn badge, then maybe you’ll get an accurate Original color on this bike.