1947 to 1951/1952 Kluson tuners.
Note the vertical "Kluson Deluxe" stamp down the center of the gear cover. But more importantly, notice 
the lack of a second tuner post hole on the opposite side of the gear cover (blue arrow). On the bottom side of the tuners stamped 
into the metal it says "D-169400 Patent NO" (can only be seen with the tuner removed). Often these tuners 
are often mis-identified as late 1950s tuners because of the vetical "Kluson Deluxe" stamping. Gibson used 
this style of tuner later than Fender. Fender stopped using this style in late 1951. Gibson stopped using 
this style in early 1952 (perhaps Gibson had a larger stock pile of these tuners).