Since your heads are D3VE-A2A's and your block casting date is 9A24, your motor is likely a 1979 production year engine. This assumes that the engine has never been apart since factory (no head swap, etc). To verify your engine year, you can do the following:
  • The block's engineering code is casted on the outside of the block on the cylinder bank and reads vertically. It is located next to where you'd mount your starter motor. You block's casting number (Engineering Rev) should be D9TE-AB.
  • Also, the 1979-up engines are externally balanced, so directly behind the crankshaft pulley/harmonic balancer should be a pendulum "hatchet weight" (looks like a small crank counterweight) that is part of this externaly balance design.
  • If your block's casting number is different and/or your motor is internally balanced (no hatchet weight on crank) then your motor is not likely original, but an earlier engine to which somebody swapped in D3VE heads.
Paul