1. The original "Titanium" cases showing the Connect XL. Space above for 2x optical drives.. and then see the silver blanking space below. Ive fitted a floppy in there on the older machine.
Yes I also fitted a floppy on that model.
But there was also plenty of space to install extra HDDs, albeit with the aid of adaptor plates purchased from Maplin.
(bit like pieces of Mecano)
2 original HDD slots plus 4 extra HDDs (I know, I'm greedy)
Although I did eventually change that particular case for something a "little larger"

All of the later models have practically no space at all inside.
Although with the size of HDDs being what they today, we don't now need too much extra space.
If I could trade-in my various smaller internal drives for TB HDDs then that would be my last modification.