So the units shifter got 'stuck' in reverse - gently hammered it out of reverse - H and neutral still worked - no Low or Reverse (just really stiff shifter), took it apart and found the interlock butterfly broken in half, can't find the part so found a used shifter on ebay, cleaned it and added fresh trans fluid - it moves smoothly to H, R and Low and back to neutral.

But once installed it behaves the same as the old, H and Neutral only, no Reverse or Low. So I'm figuring the problem is with the trans? While looking at the linkage while attempting to move the shifter it is apparent trying to move to Reverse, nothing wants to move as if frozen but probably worse inside the case.

Any ideas on how to proceed?