From Wiki

Dietzgen N1767 "National"

• Type: Duplex Trig (S and T on stators)
• Size: 10 Inches
• Material: Plastic
• Scales:
  • Front: S K A [ B CI C ] D L T
• HvH: variant of 3213, otherwise identical to 5

With vinyl slipcase and original box. S and T mounted on body, S calibrated against A, T calibrated against D. No scales on reverse.

Something funny is going on here. This rule has the same model number (and "National" name as the 1767P from 1943, but is, other than imprinted model number, identical to the AcuMath 400. Did Dietzgen make this rule, or did AcuMath? Is the 1767 number something Dieztgen reserved for "Cheap slide rules made by other manufacturers"?

With undated instruction manual.