Well, just read on the internet that these cars did not have headlight relays as part of the original build.  People added them when there wiring started to degrade.  Maybe this is why I could find no diagrams with the relay in it.  I will be buying a new wiring harness, so I would like to know if I should or should not include a headlight relay.  I would prefer not too to make my life easier but looking for input

@david-black David, I don't think the relay is necessary if your lighting system will be all, or nearly all, original. What year and model is your Chevy?

Mike

It is a 1939 master deluxe JA.  I’m heard YNZ is a good source for the wire harness. What is your opinion of this source

I bought my main and accessory horn harnesses from YNZ. Not inexpensive but well made with clear markings & instructions.

Tiny, thank you for your input.  From the quote I got it will be around $1,500.  You are correct in the high cost, but if they produce a quality product, then this is the right direction for me. 

I used a y n z on my 39 and it was excellent. I had a couple of questions and they were very helpful over the phone. It has been about ten years but all I have heard about them is good.

Dave