VARIATIONS

1918-26:  4-digits have no hyphen. (Except 1920 and 1924)

1920:     6-digits have thinner first "1" and no hyphen

1939 Type 1:  1939 dies   223-094 - 684-669

     Type 2:  1940 dies   685-355 - 685-470     (116 P)

1941 Type 1:  Bolt slots  208-894 - 689-348

     Type 2:  Bolt holes  701-262 - 774-163  (72,902 P)

1950 Type 1:  Steel         100-001 - 680-469,  W-1001 - W-56432,

                             R-6790 - R-72445

     Type 2:  Aluminum      713-789 - 760-000, W-71358 - W-84823

             (100,000 ordered)                     (59,678 P)

1951 Type 1:  Steel         100-001 - 731-814,  W-1001 - W-92579,

                            R-54032 - R-88943, N-13522 - N-41173

     Type 2:  Aluminum       R-1001 - R-33809, R-91653?

     Type A:  Pointed "51"  100-001 - 206-958, N-17295, N-26936,

                                               N-28807, N-33426,

                                               N-34103, N-38251

     Type B:  Flat-top "51" 215-818 - 741-640,  W-1001 - W-95956,

                             R-1001 - R-96720, N-14309, N-21066,

                                               N-37408, N-41173

1953 Type 1:  Tab slots     100-001 - 746-049,  W-1001 - W-95955,

                             R-1001 - R-40015,  N-1001 - N-97636

     Type 2:  No slots      R-57934 - R-98602      (40,669 S)

     Type 3:  Slogan         X-1395 - X-45897      (44,503 S)

1954 Type 1:  No slogan     100-001 - 588-253,

                             R-1001 - R-48470     (535,723 S)

     Type 2:  Slogan        594-689 - 739-005, R-52585 - R-88945,

                             W-1001 - W-98588,  N-1001 - N-98454,

                             X-1001 - X-97352     (460,889 S)

1955 Type 1:  1942-54 dies  100-001 - 745-000,  W-1001 - W-97063,

                             R-1001 - R-97804,  N-1001 - N-83656,

                             X-1001 - X-94982

     Type 2:  1956-85 dies   A-3340 - A-98918,

                             V-6858 - V-21954     (110,676 P)

1956:  Bolt holes up to ZM-259, ZT-3889 on

       Bolt slots ZP-5449 - ZR-3631  (8,182 S)

1957:  Bolt holes F-2354 - FF-6578, H-122 - HH-6936 (141,027 S)

       Bolt slots up to ET-922, FJ-4336 - FX-7650, HJ-8016 on

1959:  Bolt holes ZK-1961 - ZL-6141 (14,180 S)

       Bolt slots up to ZD-7253, ZF-277

1960:  Bolt holes AA-7921 - AH-6925, DR-3605 on

       Bolt slots  AJ-432 - DP-3695 (743,190 S)

1967:  HM-896 has inverted "W"

1975 Type 1:  3 dies on date observed, no exact breakdowns

             (square "5 with no bottom hook 7/16" wide, curved "5"

              with bottom hook 7/16" wide, same but 3/8" wide)

1980 Type 3:  3 dies on date observed, no exact breakdowns

             (pointed-serif "1" and space between "9" and "8",

              pointed-serif "1" with no space between digits,

              flat-top-serif "1" with no space between digits)

              Sticker bracket or sticker bar, no exact breakdowns

1983-2008 FIRST IN FLIGHT BASE

Type 1a:  Close spacing AAA-11 - HMA-11 (269,915), or (HMP reported)

          wide spacing  HMW-78 - XFR-12 (466,114).

Type 2:  Solid script  BLK-483 - CKF-556 (374,957), or

         opaque script CKV-514 - DBV-418 (264,211).

High-gloss type began between CXN and CYH, Oct.89, "OCT 90".

Short 1/2" hyphen HYS-7074, JSA-3749, JVK-3199.

Long 1" dash JSA-4989, JVK-7873. (Standard dash is 7/8")