[phat rat]

M.A.M. sorry the trailer wired that way was a long time ago, late 70's early 80's. Now I would just say no.
D_R_C you're correct about not finding them on vehicles from the factory. I think they are used primarily on semi's. I threw that out there because of your statement of "7 wire plugs are blades". You just can't be sure of what you might find out there

 

[D_R_C]

Yes, you are correct, I drove trucks for 40 years and just had a flash back after clicking on your link, my bad.
I’ve been retired for 9 years so now my focused his only been on personal vehicles.