Listed here is a USED Johnson / Evinrude lower unit for parts. It is not frozen and shifts smoothly from reverse to neutral.  You may want to fix it up a bit to use or use it for parts.  Gear oil is dark but water did not come out so I left it with the old gear oil inside so you can see it doesn't leak.  Picture of oil is in listing.  The shaft length is 21 1/2" from the top of the gear casing to the end of the drive shaft and it has 14 splines.  The prop shaft has 13 splines.  These were used on a wide variety of years from the 1970s into the 1990s on many of the two and three cylinder engines.  This one was from a early 1980s 55hp Johnson that had engine problems and is no longer with us.  Significant corrosion on shift shaft housing but shaft movement is free.  PLEASE COME SEE THIS BEFORE PURCHASING.  It may not be your cup of tea and Id like you to see it before you commit.  Thank you for your interest.  Steve MMSLLC :)