Chrysler operated multiple assembly plants in the muscle-car era, and each plant maintained its own clerical and stamping practices. The Lynch Road plant in Detroit, where most B-body cars were built, is famous for omissions. The A34 Super Track Pak axle code, for example, frequently does not appear on a Lynch Road tag even when the car was built with a 4.10-geared Dana 60 — the plant used the upper '084' axle stamping in lieu of the option callout. St. Louis and Los Angeles tags, by contrast, tend to stamp the option codes more completely.
Forum threads have argued about this for twenty years. Plenum's schema knows which plant built the car (from the eleventh VIN character) and adjusts what it considers a missing-equipment finding accordingly. A blank A34 cell on a Lynch Road sheet is not evidence of absence; on a St. Louis sheet it usually is.