I was wondering why you said they interchange up to '74? I've got one I was going to swap into my '76 Duster, and I'm not sure what year it came out of. I think a '68 Valiant. Won't it work?
(sorry about the scrapper jerks, a local race car builder had them walk off with a '69 440 bare block that he just kept outside unless he was using it to fit mounts/headers. People suck!)