I bought some replacement low profile steel Mag floor plates from Wilson Combat. The standard "polymer" floorplates get brittle as they age, and can crack or break off. Spontaneous disassembly of carry mags is a bad thing <G>. My 47D's are about 10 years old, so it was time for new ones.
There have been some subtle modifications to the 47D mags over the years, and the new floorplate came with instructions for modifying them to work with old mags. I found I did not have to perform the outlined modification. However I did have to file a bit off of the bottom rear of each Mag to allow the replacement metal floorplate to slide all the way on.
FWIW; Wilson Combat is the only place I could find that sold the low profile steel base plates separately.