The gas tanks are dated with a week and year code.
67 has a calendar week code. 16 D 7 would be the 16th week of 67, day shift. 40 6N would be 40th week of 66, night shift.
The format changed in 68 and 69 to have the week counted from the beginning of the *model* year. The extended 69 model year used tanks dated for the 70 model year.
LOS and NOR data is intermixed and shows the same pattern.
67:
11A 42 6D (stamped 42 9D)
11A 40 6N
11B 49 6
?? 52 N 6
01B 52 N 6
02A 5 N 7
02B 5 D 7
02C 5 D 7
02E 6 D 7 (stamped 7D6)
03B 9 D 7
03C 11 N 7
03C 11 N 7
04B 4 N 7
04D 5 D
05A 17 D 7
05C 16 D 7
06C 22 D 7
06E 25 N 7
68:
10A 67 42
10E 7 5 N (7 may be a 2 and 5 is upside down)
11B 68 15
11C 68 17
11D 68 19
12D 68 20
12D 68 21
01C 68 19
02C 68 27
02D 68 32
02E 68 30
02E 68 32
03C 68 34
03D 68 36
04A 68 37
04D 68 41
05C 68 42
05C 68 42
05C 68 43
05D 68 44
05E 68 46
06A 68 45
06B 68 47
07C 68 52
07D 68 52
07D 68 53
69:
09B 1 69
09B 1 69
09B 1 69
09D 5 69
10A 05 69
10A 6 69
10B 4 69
10B 8 69
10C 4 69
10D 10 69
10D 10 69
10D 10 69
11A 12 69
11B 9 69
11C 11 69
11D 14 69
11D 15 69 (stamped 69 51)
11D 16 69
11D 17 69
12A 16 69
12B 17 69
12B 17 69
12B 18 69
12C 16 69
12C 16 69
12D 19 69
01A 19 69
01B 21 69
01B 21 69
01B 21 69
01C 21 69
01C 22 69
02A 25 69 (upside down 5)
02A 25 69 (upside down 5)
02A 25 69 (upside down 5)
02A 25 69 (upside down 5)
02A 25 69 (upside down 5)
02B 25 69 (upside down 5)
02B 25 69 (upside down 5)
02C 26 69
02D 25 69 (upside down 5)
02D 28 69
02D 28 69
02D 29 69
02D 29 69
02D 29 69
02D 29 69
03B 29 69
03B 29 69
03D 28 69
03D 45 69 - replaced?
03D 33 69
03D 33 69
03E 33 69
03E 33 69
04A 33 69
04B 33 69
04C 33 69
04C 37 69
04C 37 69
04C 37 69
04C 37 69
04C 37 69
04C 37 69
05A 37 69
05A 38 69
05E 41 69
06A 41 69
06A 42 69
06A 45 69
06A 45 69
07A 48 69
08A 1 70
08A 1 70
08C 48 69
08C 48 69
08C 2 70
08C 2 70
08D 2 70
09A 5 70
09C 5 70
09C 5 70
09D 5 70
10A 9 70
10C 9 70
10D 10 70
10E 10 70
10E 12 70
10E 12 70
10E 12 70
Thanks!