I've noticed that the wiring diagrams for the old mopars are a little odd to say the least ( year to year differences and such and like this one that is different than most of the other 72 diagrams) how about this pic... it shows the relay wire routing through the engine connector ( bottom left side is the battery and the starter relay) . The pic is a little small but if you save them and magnify or PM me your email I'll zip them up and send them to you.. the diagram is for a 72...With that being said, I'd say wire it up the way the new harness is. Did you get the whole harness ( dash, engine, lighting, etc..)