Bummer, SCA drives are still relatively easy to find. I keep running across 4GB and 9GB drives from Compaq and HP servers - actually recycled about 50 of them a few months ago.
Hope you get your 6100 back up and running. I had a G3 upgrade in mine and it was a nice machine! Stupid plastic tabs break off easily though.
68k: LC, LCII, LCIII, LC475, LC630, Q650, Plus, 2x SE, SE/30, IIci
PPC: 2x Beige G3 Server, Rev. A&C iMacs, PM7300, DP 2.5 G5
PowerBooks: 150, 180, PDQ