Thank you for the link - I agree it's an interesting read about fuses, but I didn't see anything that answers my specific questions:
I am using the OEM ICOM power cable and fuses attached to my car battery - all I need to understand is what is the correct replacement fuse for the one that blew? The automotive shops and Radio Shack stock the 20 A SFE fuses - but no one has or even knows what a 20A FGB fuse is.
Use a 20A fast-blow glass fuse of the appropriate length. That's what I use in all my radios, fused on both the pos and neg leads.
Well that's weird. W9MMS's response wasn't there when I replied. Well 2 heads are better than 1, eh? :-)