For those of you in the same boat as me, I have posted up a schematic of a heater box rod for a 70 Cuda. Thanks to Cody for giving me the measurements so I can move forward with my heater install which is backing up the dash install. Thanks Cody.
Hope this helps anyone who needs to make their own because of the scarcity of this part and/or you don't want to pay 80 bucks for it on ebay.
All you need is a 1/4" steel rod and some ingenuity.
Enjoy!
B