Some time ago I found a way to mount a drive number switch for the SX-64 on a Dutch Commodore site (see here).
It was a 3 pole 4 position switch mounted at the place where the fuse used to be.
The fuse it self was left inside the SX-64.
Now I can switch the internal drive between id 8, 9, 10 and off.
You can find the story here.