Hi David I just restored my 1958 D-17. I made a completely new wiring harness for my d-17 using my Operating Instructions manual for help. There is a page in that book towards the end that tells you what wire goes were and even the correct color of that wire. If you want i might be able to scan that page and e-mail it to you.
When i made mine I used 12 gauge wire. You should have seen the wires i took out. Someone had spliced a wire from the generator that had burned in half with speaker wire. No wounder my battery wouldn't hold a charge. Also the back of my dash was solid rust from sitting outside. That rust was shorting out the amp gauge and the battery.
Let me know if I can help.
Do it yourself and save money as well as learn a new trade. If i can do it so can you.