I have both the engine harness and forward lamp harness from Evans. Some of the C-Body parts are unique and they had to reuse a couple connectors from mine but the finish product looks NOS.
My rear body harness was done at M&H and also looks NOS and also had to reuse a couple sockets.
M&H doesn't deal direct but this isn't one that Year One sells so they did it. Not sure what their plan is now they know what a 69 Polara/Monaco rear body harness looks like. I gave them a few ratty ones to work from).
From Evans, forward lamp
From M&H, rear body
At the time I contacted M&H I didn't know Evans did rear body harnesses, they didn't always.
I'd check with them first.