Randy,
Just guessing but, could the rod in the trans have a tapered end that, when the adapter is installed, pivots the top, rounded portion of the lever into a position that is closer to the trans output/tod input shaft, thereby retaining or positioning something on the shaft?
What is the brass-colored thing at the top? A sensor?
Could the lever be doing something (positioning/retaining?) the part that the brass thing is riding on or sensing?
What does the end of the trans look like?