need help finding a small swivel!!!

[GM Muscle]

I've searched high and low and cant find anything like I'm looking for! i am building an adjustable spoiler for my car and want the struts to go from the deck lid to the spoiler. i already ordered these with matching heim joints.

they will be mounted to the deck lid.
now for the spoiler mount i have the heims but by the time i build a bracket i think it will just be too bulky for my taste. I'm basically trying to find a small joint that will accept a small rod. kind of like like a steering u joint but it only has to pivot one way and needs to accept a 5/16 rod. i would actually prefer it to be female.. imagine if you will a 1/4" swivel for a socket. but instead of the square male and female ends, its threaded instead. or I'm game for any other ideas you gurus have..
please excuse my fast drawing:

i would really prefer something like this:

Ive looked at longacre and cant justify spending over a $100 for something that isnt really what i need.