I was wondering if there is a vendor that sells a correct style proportioning valve electrical pigtail? I have a customer with a 73 Cuda that will require one real soon.

Google results show universal types and I see that Zip Corvette does them for the 69-73 Vettes. Doesn't appear that Evans Wiring offer these, and they, if anybody, would probably be the "go-to" for Mopars.

Thanks in advance!

Do you mean the cap type that connects to & covers a stud-type terminal ?
Same connector is used for temp sender, though IIRC the wire color is different.
Maybe it's listed that way ?

Stud type terminal yes.

IIRC the temp sensor is a 90 degree insulated boot type.

This connector/boot is a straight shot onto the stud and IMHO somewhat more bigger and shallow to fit over a seat. Hopefully that makes sense.

Here's a link to the Corvette piece. https://www.zip-corvette.com/69-73-proportioning-valve-plug-w-pigtail-harness.html
Might possibly work but the lead wire is incorrect color. Though a "Sharpie" could probably rectify that lol.

Yes, a 90 on the temp sender wire boot.
The Vette one seems reasonable - Sharpie, black paint, shrink tubing...