Well, my curiosity has lead me to another question with regard to the '59 & '60 Cadillac Cruise control option specific to the interior control switch assembly.
When comparing the housing portions, I have determined that Cadillac used different sized instrument light sockets & bulbs as you can see from my pics. Since I have several of these housings, I have found that it's a 50/50 split. Unfortunately, I haven't kept known '59 housing assemblies from '60 assemblies as they are identical in every other way so I am unable to confirm the application. (Although I do believe the majority of my housings are 1960).
Does anyone know anything more about this or how this may have evolved?
My assumption is the obvious. Cadillac used the smaller socket/bulb initially in 1959 applications & probably due to owner complaints,(faint light) switched to the larger socket/bulb later in '59 or for the '60 models.
Perhaps another matter to consider if you are looking to acquire this option....
I looked it up in my '60 Master Parts List. '59 & '60 used the same 57x lamp.
I bet the sockets are the same and previous owners/mechanics replaced lamps with what they had instead of what was supposed to there.
David