thanks David...
i looked at my oldest Lionel catalog (1928) and sure enough they were still in use then, but in my defense not as boldly advertised as the 1923 catalog you pictured. looks like they were used up until 1936 changing in 1937 to a so-call universal lock-on ... maybe due to T-track?
sort of surprised not to find an "L" somewhere on it.
cheers...gary