FBtc0000998 (DGRC stock #998) was set up as the platonic ideal for the original Kc cell line, which no longer exists.  It is meant to correspond to the line from which the various Kc lines now available at the DGRC and elsewhere were derived. The only paper that is clearly associated with FBtc0000998/DGRC stock #998 is FBrf0020278, which describes the generation of the original Kc cell line, but I have also included on the webpage for DGRC #998 a few papers that the Echalier laboratory and its associates published prior to 1980 that describe experiments on Kc cells; these papers describe experiments done in or in collaboration with the laboratory in which Kc cells were established, soon after the establishment of the line, and can therefore be assumed to use cells very similar to the original Kc line.
There are innumerable Kc sublines and clones mentioned in various papers, and in most cases I have no idea which of them are the same. “Kc0” is a particular problem; the name is used to describe multiple independently derived sublines selected in various labs for growth in the absence of serum, and as a result the name is pretty meaningless.
Kc167 (FBtc0000001, DGRC stock #1) is a clone made in Goldschmidt-Clermont's lab sometime in the early 1980's.  I have been told (I do not remember the source) that its name simply meant that is came from passage #167 of the line.  As far as I am aware, its first appearance in the literature is in the paper of Bourouis and Jarry, 1983, (FBrf0039281); Marc Bourouis gave me the line when I visited his lab soon after the publication of that paper.  The cells from Goldschmidt-Clermont were adapted by Bourouis to a higher pH (similar to that of mammalian cell culture media); they were returned to normal Drosophila culture medium in the Cherbas lab. These are the only Kc cells Cherbas lab has used since we got them; the cells were much easier to transfect than the Kc-H cells (see below) that we had been using previously, and their ecdysone response (which we were studying) was indistinguishable from that of Kc-H cells.  Any modENCODE paper that refers to Kc cells actually used Kc167, because Kc, like S2-DRSC, was one of the 4 designated core lines for modENCODE, used by all the modENCODE laboratories.
Kc7E10 (FBtc0000182 = DGRC stock #182) is a clone made from Kc cells (unknown isolate) in Denny O'Connor's lab probably in the 1970s or early 1980s.  It ended up in the lab of John and Lislot Fessler -- the Fesslers and O'Connor were all at UCLA.  The Fesslers worked on the biochemistry of Drosophila extracellular matrix for many years, and somewhere along the line discovered that this clone was a particularly rich source of ECM.  It has been used mainly by their group for that purpose.
I have found references in the literature to “Kc23” and “Kc161”; I suspect that these names refer to passage number. It is possible that “Kc161” is just a typo for “Kc167; I have found references to it in 3 papers from Geneva and Basel around 1980.  Kc23 appears in at least 8 papers, mostly from people associated with the Echalier lab, from which Kc originated.
There are a couple of Kc isolates that are not in the DGRC collection but which I can identify when they show up in the literature.  Kc-H is the name given by the Cherbas lab to the Kc cells obtained in 1975 from Charlie Thomas (Harvard Medical School), who got them sometime earlier from Echalier; the H stands for Harvard.  We (the Cherbas lab) used that isolate until we got Kc167 cells in 1984.  We used the name Kc-H in some of our early papers.  Kc-A4E6 is a clone that we made from Kc-H; we used it only briefly, and I don't remember whether we used that name in any of our papers, but I definitely came upon it in at least one paper from a lab that we gave the cells to.  Both Kc-H and Kc-A4E6 still exist in the Cherbas lab freezers and could probably be recovered if there were any reason to do so.
Kc cells were nowhere near so widely distributed as S2, and probably did not develop so many differences among the various labs that were growing them.  There are a lot of variant names, each used in only a few papers, and it is possible that several of the names refer to the same cells. I would imagine that most of them will end up listed as unspecified Kc, and I'm afraid that list will include more than half of the Kc literature.