I am unaware of such a diagram. And remember there are FAR more grounds than just those completed by wires, if that's all you're looking for. In fact I'd say the vast majority of the grounds on these cars are not completed by wires at all...they're switch bodies, bulb sockets, the tail lamps themselves, the horn relay case, the engine block, the alternator case, radiator support, instrument panel...etc etc etc...

Any place that one rusted (or freshly painted) part is bolted directly to another could be a compromised ground path, if it is an electrical item.