On the back side of the tuner's main plate there are patent number of "Patent Appld" stampings, depending on the year of the tuner. This info is not covered here because the numbers vary depending on the exact style of Kluson tuner. All the info below applies to all styles of 1947 to 1964 Kluson Deluxe closed-back tuners, as used on Fender and Gibson guitars of the time. All pictures by TWitrock (thanks Tom!) and some of this information was provided by L Gatanas and TWitrock.

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). Notice the bottom of the gear cover has an external "PAT. APPLD." stamping. On the bottom side of the tuners stamped into the metal it says "2356766 PAT. APPLD." (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).

1952 to 1953 Kluson tuners.
By early 1952 the vertical "Kluson Deluxe" is now gone, as is the exterior "PAT APPLD" on the botton of the tuner gear cover. There is still no second tuner post hole. On the bottom side of the tuners stamped into the metal it says "2356766 PAT. APPLD."

1953 to mid-1956 Kluson tuners.
A second tuner post hole is added to the gear cover. No vertical "Kluson Deluxe" marking. On the bottom side of the tuners stamped into the metal it says "2356766 PAT. APPLD."

Mid-1956 to late-1958 Kluson tuners.
A vertical single line "Kluson Deluxe" down the center of the gear cover is added. On the bottom side of the tuners stamped into the metal it says "2356766 PAT. APPLD."

Late-1958 to mid-1960.
On the bottom side of the tuners stamped into the metal it says "D-169400 PATENT NO." (the patent was granted and hence the tuner reflects this). Single line "Kluson Deluxe" in a single vertical line on the ribbed metal tuner cover. Tulip plastic tuners knobs have a single ring around them.

Mid-1960 to 1963:
No picture. If the tuner used Tulip tuner buttons, now they are double-ring style. On the bottom side of the tuners stamped into the metal it says "D-169400 PATENT NO."

1964-1969:
"Kluson Deluxe" is in two vertical lines on the tuner housing. These are known as "double line" Klusons, where the prior pre-1964 variant is known as "single line" Klusons. Below is a picture of these 1964-1969 style Kluson tuners with double line "Kluson Deluxe" and metal buttons.

1969-1974:
Now a double lined "Gibson Deluxe" replaces the double line "Kluson Deluxe". Also the bottom side stamp "D-169400 PATENT NO." is much deeper and bolder. The base plate for the tuners also has a more rounded look to it with the edges less defined. This happened because the dies that stamped out this part were wearing out. The original Kluson tuners company went out of business in 1974 so this style of tuner was not made again until the 1990s when WD Guitar Products bought the Kluson name (and reissued these tuners). Below is a picture of these 1969-1974 "Gibson Deluxe" style Kluson tuners with double ring Tulip buttons.

1950s Kluson Tuner Buttons.
It is very common for the Keystone style plastic tuner buttons used on Kluson tuners from 1958 to 1960 to brown and shrink and crumble. Here is a picture of an original 1956 Kluson tuner button (left) that has maintained its shape and size, versus a 1959 Kluson tuner button (right) that has deterioated. The 3-on-a-strip style Kluson tuner buttons also did this, but in the 1950 to 1957 era (by 1958 the 3-on-a-strip tuner button plastic seems to be stable today and does not deterioate). This just shows minor changes in plastic formulations made a big difference in the longevity of these plastics.

1960 Kluson keystone tuners ("double ring, single line") with buttons that have shrunk and deterioated. By 1961 the plastic changed so this is no longer a problem.