If its a 69 water pump it will be cast iron. 70 and up is aluminum. Very cool it's a 340! Depending on what you have for pulleys and brackets, it MIGHT be a bit of a puzzle as the different years of water pumps were SLIGHTLY different sizes.
Good luck, enjoy!
Yes it’s a 340 and from what I gather from my dad it came out of possibly a 72-73 dart but the water pump replacement to match I got from a 69 dart I believe
