I have A similar project , 01 HD road king / 01 HD factory sidecar. NOT A EXPERT but here is how I modified the rear brake master cylinder ( in ord...

Ok, I tried to find this harness no Go. Will put it together myself , ordered connectors and terminals from Namz . $112.00

Flyingmonkeys thank you so much for your help , will call Lewis ASAP

Thank you Smitty901 for the good advice.

Couple pics of project/photo upload test.