M-code Dart, Barracuda 69 440 bare block

I've never seen a block like this in a M-code car. The only blocks that I have seen like this were in late model C-Bodies in fact I have one out in the garage but I don't remember what year it's from. My car has the original motor mount that required me to drill and tap the two oil pump bosses. The real answer to this might be the vin number but if it's only partialy stamped stamped it could be from a 6 pack car.