This side was a bit more difficult than the other side was to mount the heat sink segments.  One thing that made it tougher was the second regulator is much closer to the front of the case that the second driver transistor was on the other side of the case.  This put the mounting screw dead center between two heat sink segments.  I had to move the first segment back to get enough material for the mounting screw.  And of coarse this pushed the middle segment over the .5" hole in the side of the case.  Off came a row of fins.  The last segment lost two rows of fins so it wouldn't stick out past the rear of the case.

Started by determining the locations of the TO-220 mounting holes.  Next drilled them for the pilot holes.
The second regulator is close to the front of case requiring the first heat sink segment to be moved to the rear to get enough material to tap into.  Also used a third screw up front to help keep the heat sink flat against the case wall.
The first segment in place.
Because the first segment was pushed back had to take a row of fins off the middle segment so it would not over lapped the exit hole in the case side.
Middle segment drilled and tapped, and mounted into position.
The rear segment had to loose a couple of rows so it wouldn't stick out past the end of the case.  Being there was only one transistor I needed another mounting screw to hold it in place also.
An inside view.
All three segment in place.  Didn't loose any fins to mounting screw positions either.
With the lid on just to make sure all clears.