modify 65 column dual cable shift for later single shift 904

What was the old transmission doing wrong?
Not sure. The previous owner had it on jack stands for 5-6 years. He never drove it and claimed that it would not shift out of park. He pulled the linkage/pan and said something fell out. He did not know where the broken part was so I was not sure where to start fixing it. I've since pulled the trans and its sitting on my garage floor.