from my notes...
Over the decades I have taken note of three different “COBRA” mascot emblems included in Cobra accessory induction kits. Which parts were used depended on what Shelby American was using at the time in new cars apparently.
S1CS-19523-B version 2, a Cobra production part during 1963 (not rare, offered as a service replacement until at least 1968) (note: There have been reproductions.)
S1CS-19523-C, a Cobra production part mid 1963 until mid 1965 (very rare not on an original Cobra) (note: There have been reproductions.)
C3RA-14225-A, a 427 Cobra production part and retail market accessory, at some point in early 427 Cobra production through 1967 (not rare as Ford sold countless numbers of them, however quality of details went down over time) (There have been way too many different reproductions of this type to count. There are reproductions of reproductions of reproductions in the replicar market.)
Ford advertising used pictures or artistic renderings of the S1CS-C emblem into 1966 and beyond. The advertisement might show S1CS-C art and the parts being packed at the time could get C3RA-A parts.
"S1CS-19523-B Emblem, AC_Cobra 2 9/16" - as contracted by Mr. Shelby locally legend says and used on most west coast cars prior to at least CSX2133. A key feature of this part family was the new design had to be large enough to cover the holes in the coachwork or damage to paintwork left by removal of mascot emblems installed by AC Cars. The reason was simple, to eliminate the need to do metal and paint repair before installing S1CS-19523-B emblems where AC Cars mascots had been previously. There are three "original versions" of this part. The series started with smooth chrome plating and a rounded exterior edge, next was sharp corner exterior edge with brushed satin chrome plating, and finally a return to smooth chrome plating but this time the outer edge was left much sharper than that of the first version. Both the second and third versions were available as service parts well into 1968.
In the book COBRA PILOTE: THE ED HUGUS STORY it is claimed that the original rounded corner smooth chromium plated version was discontinued due to cost to be replaced by the brushed finish part. Why the third sharp cornered smooth chromium plated version was introduced is a mystery. (Cobra Kit Note: Some of the “COBRA” accessory induction kits Ford and Shelby sold, assembled by the contractor Dearborn Steel Tube, retail included a medallion kit comprised of two of these emblems and four Tinnerman® brand push on speed nuts. At some point Ford stopped including this part in induction system kits and started using the emblem that superseded it.)
"S1CS-19523-C Emblem, AC_Cobra" - as designed by Mr. Brock. Legend says Mr. Brock hated the S1CS-B part and that Mr. Shelby gave him the go ahead to design something he liked better. CSX2133 is the first chassis known to have received this third design. We only know that because CSX2133 was a press car used for promotional work and clear photos of emblems and the chassis number markings just happened to get published in a magazine road test article. (Cobra Kit Note: Some of the “COBRA” accessory induction kits Ford and Shelby sold, assembled by Dearborn Steel Tube, retail included a medallion kit comprised of two of these emblems and four Tinnerman brand push on speed nuts.)
”Ford C3RA-14225-A 2”. The C3RA-14225-A part was produced in a single cavity permanent mold by one of FoMoCo's trim suppliers at the time. It replaced the S1CS-19523-C part during 427 Cobra production and became the service part for all cars eventually. (Cobra Kit Note: Some of the “COBRA” accessory induction kits Ford and Shelby sold, assembled by Dearborn Steel Tube, retail included a medallion kit comprised of two of these emblems and four Tinnerman brand push on speed nuts.)
Just in case you are using new old stock emblems from a Cobra induction kit to replacement emblems on an original Cobra or 427 Cobra; I am 98% certain that the Tinnerman push on nuts supplied in kits were not the same ones used against the aluminum coachwork of Cobras. The kits nuts are usually dyed black phosphate and oil protected. The ones I removed from Cobras or still on unrestored cars were olive drab dichromate finished to go against bare aluminum.