67 dart transmission

If the linkage is all there, but it doesn't downshift when you step on it then it should be fine.
One easy way to tell if there is no major problem with the TP ("kickdown") is if it shifts later when you step on it more.
If it does, then the TP is working and it's not a huge deal.

Now if it shifts at the same speed no matter how much throttle you give it, then there's a problem.