If you mean a bolt-in, there isn't one. They all require some work to install.
You could do what Don C. did and add a T5, you could go to Wicap and get an adapter for a GM automatic
http://www.wilcap.com/chryslerfh.html#230350BOPAT
or a GM manual
http://www.wilcap.com/chryslerfh.html#230350MT
And the base Chrysler Royal had a regular 3 speed standard transmission behind the Fluid Drive instead of the semi-automatic M6, so you could use that but it, too, requires some modifications.