Mike,
The difference is where the drain hole is. On the KF 100100 and 100101 the drain hole is on the side. (Opposite sides for each of the Part Nos.)This allows them to be mounted on the side of Bumper Guards (Bumperettes). The ones you are asking about have the drain hole on the bottom. This is common to the mounting bracket/stud. I know Larry Braker has a NOS set of these in his Golden Dragon. I do not think he is willing to part with them. He got them from me in trade for some Henry J parts I needed. I think Rudy may has a set of these as I had him check to see if he had any 100100/100101 Backup lights. He came up with only the ones you are asking about. This was over 2 years ago.
Best of luck,
Mark