John,
The 0HBB date would translate to
0 = Year (1970)
H = Month (August)
B = Week of the Month (2nd week)
B = Work Shift (2nd shift)
If you wanted a December 67 stamp, 7M would be correct with any combination of the week and shift. of course depending or your scheduled build date.
Week of the month A, B, C, D, or E
Shift A, B, or C