Were any contenders ever produced without the selector switch on the hammer, if so in what years????
Not to my knowledge but there might have been some proto types that few of us would be aware of. ....
Prior to the selector switch, on the hammer, there were two previous issues. As mentioned, the first, was a small slide bar on the hammer and then a slotted selector. When all these changes came to about, I really do not know.
Perhaps check a Blue Book and see they can shed some light.
The last time I communicated with TC, they claimed that some of this info, was lost in the "Big-Fire". ....
Be Safe !!!