sorry can't help on the Toshiba system disk, as I'm a predominantly
Amiga guy here.
DSDD 3.5 drives are rare too, as most dealers threw them away. I have a
small stash, but I'm haning on to them as they are used in Amigas.
I'd reccomend finding some computer swap meets, hamfests, and used
computer dealers. any one of these may be able to help you find what
you're looking for.
Gary Hildebrand
st. Jsoeph, MO