I am not sure which die it is - To be totally honest, I pulled this from a roll, stuck it an a 2x2 and didnt give it a thought until today.
The coin is not a doubled die and the only die CONECA has listed for 1974 is SDR-001 (A series Doubled Die Reverse) Denver has but a single obverse die (DDO-001) and two reverse die's (SDR-001 and DDR-001) What you have there appears to be some type of die damage. Perhaps you should consider submitting it to CONECA for examination and attribution.