Modifying 68'+ A body rear control arms to work on a 67'??

[Nicks67GTO]

I picked up a brand new set of Edelbrock UCA's for a really good price an Craigslist. They are the 68' and up A Body model and are verified at 10.25" center to center right now. I need to make these work on my 67' GTO which requires a starting point of 12.75" center to center.

I talked to QA1 {who now make the same Edelbrock UCA with the QA1 name} and they will not sell me just the middle portion of the adjustable control arm for some reason. They did tell me that the only difference between the 68+ and the 67' arms is the coupling in the middle. So my question is.....what material would you use to make a coupling? I have access to a machine shop/tool makers to do this correctly, i just need to know where I can find material to make the middle coupling? Do they sell this stuff somewhere online?

For reference here a pic. I'm trying to replace the red portion on these arms with something to elongate them by 1.5"

Any suggestions?

https://static1.pt-content.com/images/pt/2013/03/20130320_095640_799_zps9b7ca28a-1.jpg

[UMI Tech]

We use 4140 chromoly for our adjusters in that location.

[chevelletiger]

steel hex or aluminum hex bar,drill in a lathe then use a 3/4- lh rh tap done.

[MrQuick]

...or just open up your Coleman catalog and order 2 trailing arm links. I believe they are 3/4" threads. You will have to figure how much longer you will need.

http://www.colemanracing.com/Trailing-Arm-Hex-P3756.aspx

[chevelletiger]

oh yeah forgot about coleman.