What are the plymouth dash wiring harness differences from 74 to 75

Let's face it they all start out as bare bodies at the factory. Splice add and delete as necessary for his options. Anything would be better than a butchered up melted mess, I would think. Like 67Dart273 said no easy answer, wire by wire but unfortunately you have to have the other one out first. And then there's going to be the unknowns and electrical gremlins. If this guy wants an easy plug and play and he's a good friend, I would be careful.