Trying to track down all the different Fisher model integrated amps is a bit of a task.
Here are a couple of links that will give you some background on Fisher units.
http://fisherdoctor.com/fisher.html
http://en.wikipedia.org/wiki/The_Fisher
As for the specific Fisher integrated amps, I expect that there is some thread here that has a list of the different models, so try doing a search. However, this is a quick run-down from what I can gather - there could be lots of errors in this, so please take as a draft. I expect there will be others that are missing from this list and no doubt other more knowledgeable AKers will fill in the gaps & correct any errors:
X-100 A: Tubes 7189(4) & 12AX7(5)
X-100 B: Tubes 7868(4) & 12AX7(6)
X-100 C: Tubes 7868(4) & 12AX7(6)
X-100-2: Tubes 7189(4) & 12AX7(5)
X-100-3: Tubes 7189(4) & 12AX7(5)
X-101: Tubes 7189(4), 12AX7(6), GZ34
X-101 A: Tubes 7189(4), 12AX7(6)
X-101 B: Tubes 7591(4), 12AX7(6), GZ34
X-101 C: Tubes 7591(4), 12AX7(6)
X-101 D: Tubes 7591(4), 12AX7(6)
X-101-ST: Tubes 7189(4), 12AX7(6), GZ34
X-202: Tubes 7189(4), 7247(2), 12AX7(6), 12AT7(3), GZ34
X-202-B: Tubes 7591(4), 7247(2), 12AX7(6)
X-202C: Tubes 7591(4), 7247(2)
KX-90: Tubes 7189(4) & 12AX7(5)
KX-100: Tubes 7868(4) & 12AX7(6)
KX-100 B: Tubes 7591(4), 12AX7(6)
KX-200: Tubes 7591(4), 12AX7(6), + Bias Meter
X-1000: 6CA7(4), 12AX7(5), 7247(2), EF86(2), 12AU7
K-1000: 8417(4), ELL80(2), ECC83(2), ECC808??
SA-1000: 8417(4), ELL80(2), ECC83(2), ECC808
I think the KX models are kit versions of some of the X models. :scratch2: While many of the above models seem to have a similar tube complement, I believe that there are other differences such as faceplates, connections, etc. Out of these, I only have the KX-200, so cannot really comment on which might be the better sounding, or built.
Some of these are harder to come by than others. Often the ones with the GZ34 rectifiers seem to go higher in value, especially if the GZ34 is Mullard or similar high value old stock, or if the 12AX7s are Teles, Mullards, etc. Also, the 7247s are relatively scarce. 7189 tubes are long out of production but some use EL84/6BQ5 tubes, others prefer EL84M or the Russian military 6P14P-EV. As for the others, there are old stock and new production versions of the 7868 and 7591 tubes, as well as many choices for 12AX7. For the last three on the list - they are scarce. Actually the 8417 ones are power amps, not integrated, so shouldn't be on the list, and the tubes in those are harder to get & pricey.
In your search, you might want to take a look at other integrated amps such as from Sherwood, H. H. Scott, Harman Kardon, Pilot, Stromberg Carlson, EICO, Bogen, Knight, Pioneer, Sansui etc. There are some good models and sleepers among them.:thmbsp:
I hope this helps. Good luck & have fun in the search!