I think Kodak 4168 was discontinued and replaced by SO-339. I could be
wrong. The 4168 film gave me good results, and unless I imagined it, the 339
film seemed to require longer exposures. I haven't bought any SO-339 (8x10)
since 1993, but I think kodak still makes it. The film's contrast can be
adjusted through development. I know some people have problems with this
film, but since I was making gum prints I was able to adjust contrast through
printing -- but it is always better (and easier) to work with a good neg.
-janice