P code Big Block Duster ????

I just bought a 70 Duster and misc parts from a guy yesterday . In addition to the 70 he has a 73 0r 74 Duster that has a lot of good parts that im probably going to buy too . My question is the engine code is clearly a P which indicates to me a 400 car . Ive never heard of a factory big block duster . Was there such a car ? I was just going to part and scrap it , but maybe thats a bad idea . Is this something of value ? It has no engine or trans and is not worth much to me besides center console , bucket seats , 1 / 4 panels , fenders , misc small parts etc . Any general advice or feedback ?? Thanks in advance ..