Bottom collar for 4 speed key out function - auto to manual conversion

I find myself in need of a bottom collar for a 4 speed. I am ok to convert one of the multiple bottom collars if I knew what was needed beyond cutting the shifter hand off and filling it.

My '74 has the finger lever to turn the collar and unlock the key so it can be removed, but all of the how-to's I find for converting to a floor shift just cut the lever off and don't do anything with or about that function. Not really even sure how it works and if it it necessary. But I would like keep the functionality if possible on the '73.

Anyone have a how to or info on this part of the column?

I have the top two collars already, just not the bottom one. I would entertain buying one if someone had a source for just the bottom collar, but everything I find has all three for more money than I want to spend.