I pulled this topic over from the ''Lite House Trailer Manual'' thread, in case it was missed by someone who knows something about (9-pin) electrical
connections to tow vehicles.
Ray Horner did post this diagram, which I'll copy here again:
I found something similar on a website about old Avions, but my googling brought up little else.
Dena's already inquired of the U-Haul
hitch installing people in her area. (Perhaps she should try Albuquerque? :crazy-ii )