Back in the 80s, when a shop that built conversion vans was closed there was a sealed bid auction on a lot of left over stuff. I got a unopened dealer install type cruise control kit for Dodge van. I have all the cruise control from a 75 Valiant Brougham with slant 6 too. To this day I dont know how much of it is the same/interchangeable. I know neither upper cable will attach to my 67 speedometer. I doubt either lower cable will attach to my 67 trans.
I should have kept the aftermarket cruise control that was in our 1st 67 notch. It worked perfectly.